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Glyphosate suppresses the antagonistic effect of Enterococcus spp. on Clostridium botulinum
Abstract
During the last 10 to15 years, an increase of C. botulinum associated diseases in cattle has been observed in Germany. The reason for this development is currently unknown. The normal intestinal microflora is a critical factor in preventing intestinal colonisation by C. botulinum as shown in the mouse model of infant botulism. Numerous bacteria in the gastro-intestinal tract (GIT) produce bacteriocines directed against C. botulinum and other pathogens: Lactic acid producing bacteria (LAB) such as lactobacilli, lactococci and enterococci, generate bacteriocines that are effective against Clostridium spp. A reduction of LAB in the GIT microbiota by ingestion of strong biocides like glyphosate could be an explanation for the observed increase in levels of C. botulinum associated diseases. In the present paper, we report on the toxicity of glyphosate to the most prevalent Enterococcus spp. in the GIT. Ingestion of this herbicide could be a significant predisposing factor that is associated with the increase in C. botulinum mediated diseases in cattle.
... In previous studies, it was discussed that pathogenic bacteria are likely to be more tolerant to glyphosate (Krüger et al., 2013b;Shehata et al., 2013). Shehata et al. (2013) found higher MIC values in strains of pathogenic species like different Salmonella serovars and C. perfringens compared with, e.g., enterococci or lactobacilli. ...
... Shehata et al. (2013) found higher MIC values in strains of pathogenic species like different Salmonella serovars and C. perfringens compared with, e.g., enterococci or lactobacilli. Krüger et al. (2013b) confirmed the differences in sensitivity between Clostridia and enterococci. However, pathogenic and non-pathogenic strains of the same bacteria species were never investigated. ...
Glyphosate is the most extensively used herbicide in the world. However, concerns regarding its safety, side effects, and impact on other organisms have increased in recent years. This is the first study to analyze a large set of recent and historical Escherichia coli isolates varying in pathogenicity and beta-lactam resistance from different host species for their susceptibility to glyphosate isopropylamine salt (IPA), the active ingredient of the herbicide, and to a complete glyphosate-containing formulation (Roundup LB Plus). For this, minimum inhibitory concentrations (MIC) were determined for 238 E. coli isolates by broth microdilution in Mueller Hinton I media followed by the statistical analyses using Mann-Whitney-U test, multivariable analysis of variance (ANOVA) and a multivariable proportional-odds ordinal regression model. While the overall MIC distribution was narrow and lacked a highly resistant sub-population for both substances, statistical analyses revealed small but significant associations between glyphosate resistance levels and different factors tested. Mean MIC values for the entire dataset showed a higher level of resistance to the complete glyphosate-containing formulation (40 mg/ml IPA) than to pure glyphosate (10 mg/ml IPA) in E. coli. Isolates that originated from poultry had significantly higher MIC values for both pure glyphosate and the complete formulation. Pathogenic and non-extended-spectrum beta-lactamase (non-ESBL) E. coli isolates each showed significantly higher MIC values compared to commensals and ESBL-producing E. coli in pure glyphosate, but not in the complete formulation. Recently sampled isolates showed statistically higher MICs than the isolates of the historic standard E. coli collection of reference in pure glyphosate, when tested by nonparametric Mann-Whitney-U test, but not in the multivariable model. Further investigations are necessary to confirm whether these associations have a casual relationship with the glyphosate use or are the consequence of co-selection due to the increased application rates of antibiotics, heavy metals or other biocides. A possible accumulation of pathogenic bacteria in livestock animals fed with glyphosate-containing feed should also be considered.
... However, the largest amounts of antibacterial substances are present in industrial agricultural production systems where GM plants with tolerance to glyphosate-based herbicides are grown. Glyphosate is known to have significant antibacterial effects [44] and to affect bacterial communities either in soils (e.g., [45]) or in intestines of mammals (e.g., [46][47][48]. Recently, researchers found that glyphosate significantly decreased the intestinal bacterial diversity also of an insect species, the honey bee (Apis mellifera) [49]. ...
The insecticidal crystal proteins from Bacillus thuringiensis (Bt) are widely-used biopesticides that are used both as Bt spore-crystal preparations in sprayable formulations and as activated toxins in genetically modified (GM) plants. Models for their modes of action have been proposed but many issues remain unresolved. Among those is the role of commensal gut bacteria in target insect death: previous studies showed that antibiotics attenuate the toxicity of Bt sprays. We tested whether antibiotics interfere with the effects of GM plant-produced Bt toxins in larvae of two Lepidopteran species, the European corn borer Ostrinia nubilalis and the cotton leafworm Spodoptera littoralis. The larvae were reared on artificial diet with or without antibiotics and, thereafter, fed two varieties of Bt GM maize in comparison to conventional non-Bt maize leaves sprayed with antibiotic solution and/or with a Bt formulation. Antibiotics significantly reduced or delayed the toxicity of Cry toxins, although to a lesser extent than previously reported for Bt-sprays. This supports the hypothesis that Cry toxins induce mortality by themselves in the absence of Bt bacteria and spores, and of commensal gut bacteria. However, larvae that were not treated with antibiotics died faster and at a higher rate which was further compounded by plant variety and species sensitivity. These findings support a hypothesis that toxicemia alone can inflict significant mortality. However, in the absence of antibiotics, the gut bacteria likely enhance the Cry toxin effect by inflicting, additionally, bacterial septicemia. This has important implications in field situations where antibiotic substances are present—e.g., from manure of animals from conventional production systems—and for ecotoxicological testing schemes of Bt toxins and nontarget organisms that are often using artificial diets enriched with high concentrations of antibiotics.
... An in vitro study on interactions between the gut bacteria, Enterococcus spp. and Clostridium botulinum, showed effects at the unrealistic concentrations of 1 Â 10 3 and 10 Â 10 3 μg/L with no observed effects at 100 μg/L in the growth medium (Krüger et al. 2013). In another example, rats fed 500 mg/kg of GBH were reported to have altered abundance and composition of gut microbiota (Aitbali et al. 2018). ...
The chemical and biological properties of glyphosate are key to understanding its fate in the environment and potential risks to non-target organisms. Glyphosate is polar and water soluble and therefore does not bioaccumulate, biomagnify, or accumulate to high levels in the environment. It sorbs strongly to particles in soil and sediments and this reduces bioavailability so that exposures to non-target organisms in the environment are acute and decrease with half-lives in the order of hours to a few days. The target site for glyphosate is not known to be expressed in animals, which reduces the probability of toxicity and small risks. Technical glyphosate (acid or salts) is of low to moderate toxicity; however, when mixed with some formulants such as polyoxyethylene amines (POEAs), toxicity to aquatic animals increases about 15-fold on average. However, glyphosate and the formulants have different fates in the environment and they do not necessarily co-occur. Therefore, toxicity tests on formulated products in scenarios where they would not be used are unrealistic and of limited use for assessment of risk. Concentrations of glyphosate in surface water are generally low with minimal risk to aquatic organisms, including plants. Toxicity and risks to non-target terrestrial organisms other than plants treated directly are low and risks to terrestrial invertebrates and microbial processes in soil are very small. Formulations containing POEAs are not labeled for use over water but, because POEA rapidly partitions into sediment, risks to aquatic organisms from accidental over-sprays are reduced in shallow water bodies. We conclude that use of formulations of glyphosate under good agricultural practices presents a de minimis risk of direct and indirect adverse effects in non-target organisms.
... The inhibition of the enzyme 5-enolpyruvylshiquimate-3-phosphate synthase (EPSPS), encoded in the plant nucleus with catalytic action in the chloroplast, interferes with the production of amino acids that are essential for the defense of plants and microbial composition, such as phenylalanine, tyrosine and tryptophan. This generates an imbalance in carbon input and, consequently, results in a high concentration of phytotoxic compounds that act in metabolic routes, such as shikimati-3-phosphate (Kruse et al. 2000;Roman et al. 2005;Bervald et al. 2010;Roso and Vidal 2010;Krüger et al. 2013;Amaral et al. 2013;Banks et al. 2014;Arango et al. 2014;Duke 2018). ...
The indiscriminate use of glyphosate is one of the main agricultural practices to combat weeds and grasses; however, its incorrect application increases soil and water contamination caused by the product. This situation is even more critical due to its great versatility for use in different cultivars and at lower prices, making it the most used pesticide in the world. Nevertheless, there is still a lack of in-depth studies regarding the damage that its use may cause. Therefore, this review focused on the analysis of environmental impacts at the soil–water interface caused by the use of glyphosate. In this sense, studies have shown that the intensive use of glyphosate has the potential to cause harmful effects on soil microorganisms, leading to changes in soil fertility and ecological imbalance, as well as impacts on aquatic environments derived from changes in the food chain. This situation is similar in Brazil, with the harmful effects of glyphosate in nontarget species and the contamination of the atmosphere. Therefore, it is necessary to change this scenario by modifying the type of pest control in agriculture, and actions such as crop rotation and biological control.
... Glyphosate is the active component of roundup (montsanto), the most widely used herbicide in the world. The growth of Enterococcus faecalis bacteria isolated from cattle and horse faeces has been shown to be inhibited by low concentrations of glyphosate (450 mg/mL) for 5 days [154]. Sensitivity to glyphosate depends on the bacterial strain. ...
Pesticides have long been used in agriculture and household treatments. Pesticide residues can be found in biological samples for both the agriculture workers through direct exposure but also to the general population by indirect exposure. There is also evidence of pesticide contamination in utero and trans-generational impacts. Whilst acute exposure to pesticides has long been associated with endocrine perturbations, chronic exposure with low doses also increases the prevalence of metabolic disorders such as obesity or type 2 diabetes. Dysmetabolism is a low-grade inflammation disorder and as such the microbiota plays a role in its etiology. It is therefore important to fully understand the role of microbiota on the genesis of subsequent health effects. The digestive tract and mostly microbiota are the first organs of contact after oral exposure. The objective of this review is thus to better understand mechanisms that link pesticide exposure, dysmetabolism and microbiota. One of the key outcomes on the microbiota is the reduced Bacteroidetes and increased Firmicutes phyla, reflecting both pesticide exposure and risk factors of dysmetabolism. Other bacterial genders and metabolic activities are also involved. As for most pathologies impacting microbiota (including inflammatory disorders), the role of prebiotics can be suggested as a prevention strategy and some preliminary evidence reinforces this axis.
... Glyphosate may also indirectly lead to increases in pathogenic bacteria. For example, exposure to glyphosate concentrations that do not inhibit Clostridium growth was associated with a decrease in Enterococcus-derived inhibition of Clostridial production of toxins, such as botulinum (100). At levels over regulatory limits, but beneath application concentrations, glyphosate also induced antibiotic resistance mechanisms in Salmonella species (101). ...
Since its initial sales in the 1970s, the herbicide glyphosate attained widespread use in modern agriculture, becoming the most commercially successful and widely used herbicide of all time as of 2016. Despite a primary mechanism that targets a pathway absent from animal cells and regulatory studies showing safety margins orders of magnitude better than many other, more directly toxic herbicides, the safety status of glyphosate, has recently been brought into question by a slow accumulation of studies evincing more insidious health risks, especially when considered in combination with the surfactants it is usually applied with. Current, official views of respected international regulatory and health bodies remain divided on glyphosate's status as a human carcinogen, but the 2015 IARC decision to reclassify the compound as Category 2a (probably carcinogenic to humans) marked a sea change in the scientific community's consensus view. The goal of this review is to consider the state of science regarding glyphosate's potential as a human carcinogen and genotoxin, with particular focus on studies suggesting mechanisms which would go largely undetected in traditional toxicology studies, such as microbiome disruption and endocrine mimicry at very low concentrations.
... The mechanism of carcinogenicity may be DNA damage that results from the increase in reactive oxygen species induced by Roundup ® and its ingredients, as shown to occur in human blood cells [125] and Drosophila [83]. Behavioral (autism, seizure disorder: [126,127], digestive [128], and metabolic complications may be related to Roundup ® -induced changes in the gut microbiome (humans: [129,130]; poultry: [131]; cattle: [132,133]; mice: [93]; and rats: [134]). Damaged kidney function seen in agricultural workers was attributed to exposure to Roundup ® along with heavy metals in the drinking water [135]. ...
Genetically modified foods have become pervasive in diets of people living in the US. By far the most common genetically modified foods either tolerate herbicide application (HT) or produce endogenous insecticide (Bt). To determine whether these toxicological effects result from genetic modification per se, or from the increase in herbicide or insecticide residues present on the food, we exposed fruit flies, Drosophila melanogaster, to food containing HT corn that had been sprayed with the glyphosate-based herbicide Roundup ® , HT corn that had not been sprayed with Roundup ® , or Roundup ® in a variety of known glyphosate concentrations and formulations. While neither lifespan nor reproductive behaviors were affected by HT corn, addition of Roundup ® increased mortality with an LC 50 of 7.1 g/L for males and 11.4 g/L for females after 2 days of exposure. Given the many genetic tools available, Drosophila are an excellent model system for future studies about genetic and biochemical mechanisms of glyphosate toxicity.
... However, changes in the microbial composition in the cow rumen have not been discovered in another study ( Riede et al., 2016). The presence of Gly on strains of enterococcal isolated from horse and cattle induced low levels of Enterococcus spp., related to an alteration in its inhibitory role against Clostridium botulinum, causing diseases such as diarrhoea or pseudomembranous colitis ( Krüger et al., 2013). ...
There are currently various concerns regarding certain environmental toxins and the possible impact they can have on developmental diseases. Glyphosate (Gly) is the most utilised herbicide in agriculture, although its widespread use is generating controversy in the scientific world because of its probable carcinogenic effect on human cells. Gly performs as an inhibitor of 5-enolpyruvylshikimate-3-phospate synthase (EPSP synthase), not only in plants, but also in bacteria. An inhibiting effect on EPSP synthase from intestinal microbiota has been reported, affecting mainly beneficial bacteria. To the contrary, Clostridium spp. and Salmonella strains are shown to be resistant to Gly. Consequently, researchers have suggested that Gly can cause dysbiosis, a phenomenon which is characterised by an imbalance between beneficial and pathogenic microorganisms. The overgrowth of bacteria such as clostridia generates high levels of noxious metabolites in the brain, which can contribute to the development of neurological deviations. This work reviews the impact of Gly-induced intestinal dysbiosis on the central nervous system, focusing on emotional, neurological and neurodegenerative disorders. A wide variety of factors were investigated in relation to brain-related changes, including highlighting genetic abnormalities, pregnancy-associated problems, diet, infections, vaccines and heavy metals. However, more studies are required to determine the implication of the most internationally used herbicide, Gly, in behavioural disorders.
... The normal intestinal microflora is a critical for preventing intestinal colonization by Clostridum botulinum, as it has been shown in the mouse model of infant botulism. In this sense, the preferential GLY toxicity to the most prevalent Enterococcus spp. in the gastrointestinal tract could be, at least in theory, a significant predisposing factor that is associated with the increase in C. botulinum [43]. ...
Nowadays, there seems to be a consensus about the multifactorial nature of autism spectrum disorders (ASD). The literature provides hypotheses dealing with numerous environmental factors and genes accounting for the apparently higher prevalence of this condition. Researchers have shown evidence regarding the impact of gut bacteria on neurological outcomes, altering behavior and potentially affecting the onset and/or severity of psychiatric disorders. Pesticides and agrotoxics are also included among this long list of ASD-related environmental stressors. Of note, ingestion of glyphosate (GLY), a broad-spectrum systemic herbicide, can reduce beneficial bacteria in the gastrointestinal tract microbiota without exerting any effects on the Clostridium population, which is highly resistant to this herbicide. In the present study, (i) we performed a systematic review to evaluate the relationship between Clostridium bacteria and the probability of developing and/or aggravating autism among children. For that purpose, electronic searches were performed onMedline/PubMedandScielodatabases for identification of relevant studies published in English up to December 2017. Two independent researches selected the studies and analyzed the data. The results of the present systematic review demonstrate an interrelation between Clostridium bacteria colonization of the intestinal tract and autism. Finally, (ii) we also hypothesize about how environmental GLY levels may deleteriously influence the gut-brain axis by boosting the growth of Clostridium bacteria in autistic toddlers.
... Numerous diseases have been hypothesized to be possibly induced by glyphosate or its herbicide formulations, e.g. renal failure [15], autism [16], celiac incidence [17], asthma [18], allergy [19], cancer [20], diabetes [15], endocrine diseases [21], intestinal infection [22] or birth abnormalities [23,24]. Several of these diseases or disorders are directly related to cellular toxicity, therefore, cytotoxicity to hepatic, hematopoietic, bone marrow, neuronal, fetal and embryonal, placental and other cell lines has become a crucial issue in risk assessment of glyphosate and glyphosate-based herbicides [25][26][27][28][29][30]. ...
Rapid and inexpensive biosensor technologies allowing real-time analysis of biomolecular and cellular events have become the basis of next-generation cell-based screening techniques. Our work opens up novel opportunities in the application of the high-throughput label-free Epic BenchTop optical biosensor in cell toxicity studies. The Epic technology records integrated cellular responses about changes in cell morphology and dynamic mass redistribution of cellular contents at the 100-150 nm layer above the sensor surface. The aim of the present study was to apply this novel technology to identify the effect of the herbicide Roundup Classic, its co-formulant polyethoxylated tallow amine (POEA), and its active ingredient glyphosate, on MC3T3-E1 cells adhered on the biosensor surface. The half maximal inhibitory concentrations of Roundup Classic, POEA and glyphosate upon 1 h of exposure were found to be 0.024%, 0.021% and 0.163% in serum-containing medium and 0.028%, 0.019% and 0.538% in serum-free conditions, respectively (at concentrations equivalent to the diluted Roundup solution). These results showed a good correlation with parallel end-point assays, demonstrating the outstanding utility of the Epic technique in cytotoxicity screening, allowing not only high-throughput, real-time detection, but also reduced assay run time and cytotoxicity assessment at end-points far before cell death would occur.
... In the case of female rats, mortality increased two to three times and pre-mature death was observed whilst, mammary tumors appeared more frequently (Seralini et al., 2014). Antimicrobial activity of glyphosate and glufosinate is another rising concern (Samsel and Seneff, 2013) as Kruger et al. (2013) clearly stated that glyphosate disrupts intestinal bacteria in cattle and poultry. Some scientists suggested altered defense response of plants against microflora (Benbrook, 2016). ...
... Also, nonmammalian animals (i.e., amphibians, fish) were found to be affected by GBH via endocrine disruption (Soso et al. 2007;Navarro-Martin et al. 2014). The glyphosate of GBH is suspected to impact microorganisms, both in terrestrial ecosystems (Newman et al. 2016a) and in the gastrointestinal microbiome in vertebrates (Shehata et al. 2013;Krüger et al. 2013b;Ackermann et al. 2015), probably because the shikimic acid pathway is present in microorganisms as well. After all, glyphosate resistance in many GMOs is based on the expression of an insensitive EPSPS from Agrobacterium tumefaciens. ...
Glyphosate-based herbicides (GBHs), consisting of glyphosate and formulants, are the most frequently applied herbicides worldwide. The declared active ingredient glyphosate does not only inhibit the EPSPS but is also a chelating agent that binds macro- and micronutrients, essential for many plant processes and pathogen resistance. GBH treatment may thus impede uptake and availability of macro- and micronutrients in plants. The present study investigated whether this characteristic of glyphosate could contribute to adverse effects of GBH application in the environment and to human health. According to the results, it has not been fully elucidated whether the chelating activity of glyphosate contributes to the toxic effects on plants and potentially on plant–microorganism interactions, e.g., nitrogen fixation of leguminous plants. It is also still open whether the chelating property of glyphosate is involved in the toxic effects on organisms other than plants, described in many papers. By changing the availability of essential as well as toxic metals that are bound to soil particles, the herbicide might also impact soil life, although the occurrence of natural chelators with considerably higher chelating potentials makes an additional impact of glyphosate for most metals less likely. Further research should elucidate the role of glyphosate (and GBH) as a chelator, in particular, as this is a non-specific property potentially affecting many organisms and processes. In the process of reevaluation of glyphosate its chelating activity has hardly been discussed.
The aim of this study was to examine the influence of glyphosate (GL) residues in feedstuffs on performance, energy balance and health-related characteristics of lactating dairy cows fed diets with different concentrate feed proportions. After an adaption period, 64 German Holstein cows (207 ± 49 d in milk; mean ± SD) were assigned to either groups receiving a GL contaminated total mixed ration (TMR) (GL groups) or an uncontaminated TMR (CON groups) during a 16 weeks trial. Contaminated feedstuffs used were legally GL-treated peas and wheat (straw and grain). GL and CON groups were subdivided into a “low concentrate” group (LC) fed on dry matter (DM) basis of 21% maize silage, 42% grass silage, 7% straw and 30% concentrate and a “high concentrate” group (HC) composed of 11% maize silage, 22% grass silage, 7% straw and 60% concentrate for ad libitum consumption. Body condition score, body weight, DM intake and milk performance parameters were recorded. In blood serum, β-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA) and glucose were measured and energy balance was calculated. Milk was analysed for GL residues. At week 0, 7 and 15, general health status was evaluated by a modified clinical score. The average individual GL intake amounted for Groups CONLC, CONHC, GLLC and GLHC to 0.8, 0.8, 73.8 and 84.5 mg/d, respectively. No GL residues were detected in milk. GL contamination did not affect body condition score, body weight, DM intake, nutrient digestibility, net energy intake, net energy balance or BHB, glucose, NEFA and milk performance parameters; whereas concentrate feed proportion and time did affect most parameters. The clinical examination showed no adverse effect of GL-contaminated feedstuffs on cows’ health condition. In the present study, GL-contaminated feedstuffs showed no influence on performance and energy balance of lactating dairy cows, irrespective of feed concentrate proportion.
Background
Glyphosate-based herbicides (GBHs) are broad-spectrum herbicides that act on the shikimate pathway in bacteria, fungi, and plants. The possible effects of GBHs on human health are the subject of an intense public debate for both its potential carcinogenic and non-carcinogenic effects, including its effects on microbiome. The present pilot study examines whether exposure to GBHs at doses of glyphosate considered to be “safe” (the US Acceptable Daily Intake - ADI - of 1.75 mg/kg bw/day), starting from in utero, may modify the composition of gut microbiome in Sprague Dawley (SD) rats.
Methods
Glyphosate alone and Roundup, a commercial brand of GBHs, were administered in drinking water at doses comparable to the US glyphosate ADI (1.75 mg/kg bw/day) to F0 dams starting from the gestational day (GD) 6 up to postnatal day (PND) 125. Animal feces were collected at multiple time points from both F0 dams and F1 pups. The gut microbiota of 433 fecal samples were profiled at V3-V4 region of 16S ribosomal RNA gene and further taxonomically assigned and assessed for diversity analysis. We tested the effect of exposure on overall microbiome diversity using PERMANOVA and on individual taxa by LEfSe analysis.
Results
Microbiome profiling revealed that low-dose exposure to Roundup and glyphosate resulted in significant and distinctive changes in overall bacterial composition in F1 pups only. Specifically, at PND31, corresponding to pre-pubertal age in humans, relative abundance for Bacteriodetes (Prevotella) was increased while the Firmicutes (Lactobacillus) was reduced in both Roundup and glyphosate exposed F1 pups compared to controls.
Conclusions
This study provides initial evidence that exposures to commonly used GBHs, at doses considered safe, are capable of modifying the gut microbiota in early development, particularly before the onset of puberty. These findings warrant future studies on potential health effects of GBHs in early development such as childhood.
Glyphosate (G) is the active ingredient of the most widely used herbicide products. It targets the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), which lacks in humans, suggesting to confer a low mammalian toxicity to G-based herbicides (GBHs). Despite this, the use of G is currently under intense debate. Many studies indicating its hazard and toxicity on non-target organisms are emerging, and associations between GBHs and immune-endocrine disturbances have been described. This review aims to investigate, based on recent epidemiological studies and studies performed in vitro and in vivo in animals, the possible association between GBHs and immune-endocrine alterations. Published data suggest that GBHs have endocrine disrupting potentiality targeting sex and thyroid hormones, although its relevance for humans will require further investigations. Evidence of immunotoxicity are limited compared to those on endocrine effects, but overall highlight possible noxious effects, including lung inflammation and rhinitis. An attractive hypothesis could be the one that connects microbiota dysbiosis with possible immune-endocrine outcomes. Indeed, several intestinal microorganisms express the enzyme EPSPS and, studies are emerging that highlight a possible G-induced dysbiosis. Considering the wide use of GBHs in agriculture, further studies investigating their noxious effects at levels relevant for human exposure should be performed. A critical analysis of emerging evidence of G toxicity is required to better characterize its safety profile. In addition, attention should be paid to the differences between G alone and its formulations, which, containing substances able to increase G absorption, may present a different toxicity profile.
The widespread adoption of genetically modified, glyphosate-tolerant corn and soybean varieties in US crop production has led to a dramatic increase in glyphosate usage. Though present at or below regulatory limits currently set for human foodstuffs, the concentration of glyphosate in companion animal feed is currently unknown. In the present study, 18 commercial companion animal feeds from eight manufacturers were analyzed for glyphosate residues using ELISA. Every product contained detectable glyphosate residues in the range of 7.83 × 10^1 to 2.14 × 10^3 μg kg^−1 dry weight, with the average and medians being 3.57 × 10^2 and 1.98 × 10^2 μg kg^−1 respectively. Three products were tested for within-bag variation and six were tested for lot to lot variation. Little within-bag variation was found, but the concentration of glyphosate varied by lot in half of the products tested. Glyphosate concentration was significantly correlated with crude fiber content, but not crude fat or crude protein. Average daily intakes by animals consuming feeds containing the median glyphosate concentration are estimated to result in exposures that are 0.68–2.5% of the Allowable Daily Intake (ADI) for humans in the US and EU, which are 1750 and 500 μg kg^−1 respectively. Consumption of the most contaminated feed, however, would result in exposure to 7.3% and 25% of the above ADIs, though the relevance of such an exposure to companion animals is currently unknown.
Companion animal feeds contained 7.83 × 10^1 to 2.14 × 10^3 μg kg^−1 glyphosate which is likely to result in pet exposure that is 4–12 times higher than that of humans on a per Kg basis.
The impairment of liver function by low environmentally relevant doses of glyphosate-based herbicides (GBH) is still a debatable and unresolved matter. Previously we have shown that rats administered for 2 years with 0.1 ppb (50 ng/L glyphosate equivalent dilution; 4 ng/kg body weight/day daily intake) of a Roundup GBH formulation showed signs of enhanced liver injury as indicated by anatomorphological, blood/urine biochemical changes and transcriptome profiling. Here we present a multiomic study combining metabolome and proteome liver analyses to obtain further insight into the Roundup-induced pathology. Proteins significantly disturbed (214 out of 1906 detected, q < 0.05) were involved in organonitrogen metabolism and fatty acid β-oxidation. Proteome disturbances reflected peroxisomal proliferation, steatosis and necrosis. The metabolome analysis (55 metabolites altered out of 673 detected, p < 0.05) confirmed lipotoxic conditions and oxidative stress by showing an activation of glutathione and ascorbate free radical scavenger systems. Additionally, we found metabolite alterations associated with hallmarks of hepatotoxicity such as γ-glutamyl dipeptides, acylcarnitines, and proline derivatives. Overall, metabolome and proteome disturbances showed a substantial overlap with biomarkers of non-alcoholic fatty liver disease and its progression to steatohepatosis and thus confirm liver functional dysfunction resulting from chronic ultra-low dose GBH exposure.
The present study aimed to characterize Enterococcus faecalis (n = −6) and Enterococcus faecium (n = 1) isolated from healthy chickens to find a novel perspective probiotic candidate that antagonize Clostridium botulinum types A, B, D, and E. The isolated enterococci were characterized based on phenotypic properties, PCR, and matrix-assisted laser desorption/ionization time of flight (MALDI-TOF). The virulence determinants including hemolytic activity on blood agar, gelatinase activity, sensitivity to vancomycin, and presence of gelatinase (gelE) and enterococcal surface protein (esp) virulence genes were investigated. Also, the presence of enterocin structural genes enterocin A, enterocin B, enterocin P, enterocin L50A/B, bacteriocin 31, enterocin AS48, enterocin 1071A/1071B, and enterocin 96 were assessed using PCR. Lastly, the antagonistic effect of the selected Enterococcus spp. on the growth of C. botulinum types A, B, D, and E was studied. The obtained results showed that four out of six E. faecalis and one E. faecium proved to be free from the tested virulence markers. All tested enterococci strains exhibited more than one of the tested enterocin. Interestingly, E. faecalis and E. faecium significantly restrained the growth of C. botulinum types A, B, D, and E. In conclusion, although, the data presented showed that bacteriocinogenic Enterococcus strains lacking of virulence determinants could be potentially used as a probiotic candidate against C. botulinum in vitro; however, further investigations are still urgently required to verify the beneficial effects of the tested Enterococcus spp. in vivo.
Aim:
This study was performed in a well-established in vitro model to investigate whether the application of a glyphosate-containing herbicide might affect the bacterial communities and some biochemical parameters in a cow's rumen.
Methods and results:
The test item was applied in two concentrations (high and low) for five days. In a second trial, fermentation vessels were inoculated with Clostridium sporogenes before the high dose was applied. Effluents were analysed by biochemical, microbiological and genetic methods. A marginal increase in short chain fatty acid production and a reduction in NH3 -N were observed. There were minor and rather equivocal changes in the composition of ruminal bacteria but no indications of a shift towards a more frequent abundance of pathogenic Clostridia species. C. sporogenes counts declined consistently.
Conclusions:
No adverse effects of the herbicide on ruminal metabolism or composition of the bacterial communities could be detected. In particular, there was no evidence of a suspected stimulation of Clostridia growth.
Significance and impact of the study:
Antibiotic activity of glyphosate resulting in microbial imbalances has been postulated. In this exploratory study, however, intraruminal application of concentrations reflecting potential exposure of dairy cows or beef cattle did not exhibit significant effects on bacterial communities in a complex in vitro system. The low number of replicates (n=3/dose) may leave some uncertainty. This article is protected by copyright. All rights reserved.
Exposure to environmental chemicals has been linked to various health disorders, including obesity, type 2 diabetes, cancer and dysregulation of the immune and reproductive systems, whereas the gastrointestinal microbiota critically contributes to a variety of host metabolic and immune functions. We aimed to evaluate the bidirectional relationship between gut bacteria and environmental pollutants and to assess the toxicological relevance of the bacteria–xenobiotic interplay for the host. We examined studies using isolated bacteria, faecal or caecal suspensions—germ-free or antibiotic-treated animals—as well as animals reassociated with a microbiota exposed to environmental chemicals. The literature indicates that gut microbes have an extensive capacity to metabolise environmental chemicals that can be classified in five core enzymatic families (azoreductases, nitroreductases, β-glucuronidases, sulfatases and β-lyases) unequivocally involved in the metabolism of >30 environmental contaminants. There is clear evidence that bacteria-dependent metabolism of pollutants modulates the toxicity for the host. Conversely, environmental contaminants from various chemical families have been shown to alter the composition and/or the metabolic activity of the gastrointestinal bacteria, which may be an important factor contributing to shape an individual’s microbiotype. The physiological consequences of these alterations have not been studied in details but pollutant-induced alterations of the gut bacteria are likely to contribute to their toxicity. In conclusion, there is a body of evidence suggesting that gut microbiota are a major, yet underestimated element that must be considered to fully evaluate the toxicity of environmental contaminants.
From 6 balance experiments with total collection of feces and urine, samples were obtained to investigate the excretion pathways of glyphosate (GLY) in lactating dairy cows. Each experiment lasted for 26 d. The first 21 d served for adaptation to the diet, and during the remaining 5 d collection of total feces and urine was conducted. Dry matter intake and milk yield were recorded daily and milk and feed samples were taken during the sampling periods. In 2 of the 6 experiments, at the sampling period for feces and urine, duodenal contents were collected for 5 d. Cows were equipped with cannulas at the dorsal sac of the rumen and the proximal duodenum. Duodenal contents were collected every 2 h over 5 consecutive days. The daily duodenal dry matter flow was measured by using chromium oxide as a volume marker. All samples (feed, feces, urine, milk and duodenal contents were analyzed for GLY and aminomethylphosphonic acid (AMPA). Overall, across the 6 experiments (n = 32) the range of GLY intake was 0.08 to 6.67 mg/d. The main proportion (61 ± 11%; ±SD) of consumed GLY was excreted with feces; whereas excretion by urine was 8 ± 3% of GLY intake. Elimination via milk was negligible. The GLY concentrations above the limit of quantification were not detected in any of the milk samples. A potential ruminal degradation of GLY to AMPA was derived from daily duodenal GLY flow. The apparent ruminal disappearance of GLY intake was 36 and 6%. In conclusion, the results of the present study indicate that the gastrointestinal absorption of GLY is of minor importance and fecal excretion represents the major excretion pathway. A degradation of GLY to AMPA by rumen microbes or a possible retention in the body has to be taken into account.
Gas gangrene is a necrotizing clostridial infection of soft tissue that affects ruminants, horses, pigs, and occasionally other mammalian and avian species worldwide. The disease is caused by one or more of the following clostridia: Clostridium septicum, C. chauvoei, C. novyi type A, C. perfringens type A, and C. sordellii. This chapter discusses the etiology, epidemiology, pathogenesis, clinical signs, diagnosis, treatment, control, and prophylaxis of gas gangrene. Alpha-toxin (ATX), a β-pore-forming member of the aerolysin family, is considered the main virulence factor of C. septicum. C. perfringens type A is associated with enteric and histotoxic diseases of humans and animals. Prevention and control should be based on immunization of the animals, on strict hygienic measures including surgical hygiene, on navel treatment with antiseptics, and avoidance of soil or fecal contamination of wounds. Proper carcass disposal helps reduce soil contamination with clostridia, but preventing predisposition is the key to controlling infection.
This chapter discusses the etiology, pathogenesis, epidemiology, clinical signs, prophylaxis and control, treatment, and diagnosis of botulism in birds and fur animals, cattle, horses and fish. Botulism can be caused botulinum neurotoxins (BoNTs), which are produced by mainly Clostridium botulinum. Exposure to BoNTs can be through ingestion of preformed toxins in food, water, or carrion; and in vivo production of BoNTs – so-called toxico-infection. The source for initial proliferation of group III C. botulinum is typically unknown. However, a common route is the contamination of feed or water by cadavers. Prevention of animal botulism can be achieved by several measures including providing safe and high quality feed and water; and properly storing animal feed. For mammalian species, treatment is carried out through the administration of antitoxin to affected animals but this has to be done when the toxin is circulating before it is bound to the neuromuscular junction.
The broad-spectrum herbicide glyphosate (common trade name "Roundup") was first sold to farmers in 1974. Since the late 1970s, the volume of glyphosate-based herbicides (GBHs) applied has increased approximately 100-fold. Further increases in the volume applied are likely due to more and higher rates of application in response to the widespread emergence of glyphosate-resistant weeds and new, pre-harvest, dessicant use patterns. GBHs were developed to replace or reduce reliance on herbicides causing well-documented problems associated with drift and crop damage, slipping efficacy, and human health risks. Initial industry toxicity testing suggested that GBHs posed relatively low risks to non-target species, including mammals, leading regulatory authorities worldwide to set high acceptable exposure limits. To accommodate changes in GBH use patterns associated with genetically engineered, herbicide-tolerant crops, regulators have dramatically increased tolerance levels in maize, oilseed (soybeans and canola), and alfalfa crops and related livestock feeds. Animal and epidemiology studies published in the last decade, however, point to the need for a fresh look at glyphosate toxicity. Furthermore, the World Health Organization's International Agency for Research on Cancer recently concluded that glyphosate is "probably carcinogenic to humans." In response to changing GBH use patterns and advances in scientific understanding of their potential hazards, we have produced a Statement of Concern drawing on emerging science relevant to the safety of GBHs. Our Statement of Concern considers current published literature describing GBH uses, mechanisms of action, toxicity in laboratory animals, and epidemiological studies. It also examines the derivation of current human safety standards. We conclude that: (1) GBHs are the most heavily applied herbicide in the world and usage continues to rise; (2) Worldwide, GBHs often contaminate drinking water sources, precipitation, and air, especially in agricultural regions; (3) The half-life of glyphosate in water and soil is longer than previously recognized; (4) Glyphosate and its metabolites are widely present in the global soybean supply; (5) Human exposures to GBHs are rising; (6) Glyphosate is now authoritatively classified as a probable human carcinogen; (7) Regulatory estimates of tolerable daily intakes for glyphosate in the United States and European Union are based on outdated science. We offer a series of recommendations related to the need for new investments in epidemiological studies, biomonitoring, and toxicology studies that draw on the principles of endocrinology to determine whether the effects of GBHs are due to endocrine disrupting activities. We suggest that common commercial formulations of GBHs should be prioritized for inclusion in government-led toxicology testing programs such as the U.S. National Toxicology Program, as well as for biomonitoring as conducted by the U.S. Centers for Disease Control and Prevention.
Two decades ago, paediatric inflammatory bowel disease (IBD) drew only modest interest from the international paediatric community. Since then, dramatically globally increasing incidence rates have made childhood-onset IBD a priority for most paediatric gastroenterologists. The emerging pandemia of paediatric IBD has fuelled a quest to identify the recent changes in early life exposures that could explain the increasing risk for IBD amongst today's children. Treatment of children with IBD should aim for symptom control but should also target restoration of growth and prevention of pubertal delay. The paediatric IBD phenotype seems to be characterized by more extensive disease location, and some comparative studies have suggested that childhood-onset IBD also represents a more severe phenotype than the adult-onset IBD form. In this review, we analyse recent global incidence trends of paediatric IBD. We present an update on the known and suggested risk factors that could explain the emerging global epidemia of paediatric IBD. We also draw attention to differences in treatment between children and adults with IBD. Finally, we highlight latest follow-up studies that question the proposed dynamic and aggressive nature of childhood-onset IBD.
Context:
Autism is a neurodevelopmental disorder for which a number of genetic, environmental, and nutritional causes have been proposed. Glyphosate is used widely as a crop desiccant and as an herbicide in fields of genetically modified foods that are glyphosate resistant. Several researchers have proposed that it may be a cause of autism, based on epidemiological data that correlates increased usage of glyphosate with an increased autism rate.
Objective:
The current study was intended to determine if excessive glyphosate was present in the triplets and their parents and to evaluate biochemical findings for the family to determine the potential effects of its presence.
Design:
The author performed a case study with the cooperation of the parents and the attending physician.
Setting:
The study took place at The Great Plains Laboratory, Inc (Lenexa, KS, USA).
Participants:
Participants were triplets, 2 male children and 1 female, and their parents. The 2 male children had autism, whereas the female had a possible seizure disorder. All 3 had elevated urinary glyphosate, and all of the triplets and their mother had elevated values of succinic acid or tiglylglycine, which are indicators of mitochondrial dysfunction.
Intervention:
The participants received a diet of organic food only.
Outcome measures:
The study performed organic acids, glyphosate, toxic chemicals and tiglylglycine, and creatinine testing of the participants' urine.
Results:
The 2 male triplets with autism had abnormalities on at least 1 organic acids test, including elevated phenolic compounds such as 4-cresol, 3-[3-hydroxyphenyl]-3-hydroxypropionic acid and 4-hydroxyphenylacetic acid, which have been previously associated with Clostridia bacteria and autism. The female, who was suspected of having a seizure disorder but not autism, did not have elevated phenolic compounds but did have a significantly elevated value of the metabolite tiglylglycine, a marker for mitochondrial dysfunction and/or mutations. One male triplet was retested postintervention and was found to have a markedly lower amount of glyphosate in his urine.
Conclusions:
The pattern of metabolites in the urine samples of the males with autism are consistent with a recent theory of autism that connects widespread glyphosate use with alteration of animal and human gastrointestinal flora. That theory is that the normally beneficial bacteria species that are sensitive to glyphosate are diminished and harmful bacteria species, such as Clostridia, that are insensitive to glyphosate, are increased following exposure to glyphosate. Excessive dopamine, caused by inhibition of dopamine-beta-hydroxylase by Clostridia metabolites, in turn, produces oxidative species that damage neuronal Krebs cycle enzymes, neuronal mitochondria, and neuronal structural elements such as the neurofibrils.
Glyphosate, the active compound of Roundup, is one of the most used pesticides in the world. Its residues are often
detected in animal feed, but the impact on the animal gut microbiota and on pathogens of the intestine has not intensively been investigated. In this study, we analyzed the minimum inhibitory concentration (MIC) of glyphosate
isopropylamine salt and a common glyphosate-containing herbicide formulation in 225 Salmonella enterica isolates
by broth microdilution. A bacteriostatic effect of glyphosate on Salmonella growth was detected at the concentration range of 10 to 80 mg/mL for both the active ingredient and the ready-to-use formulation. Time/year of isolation, host species, and serovars revealed a statistically significant influence on MIC values. Recently collected
Salmonella isolates had significantly higher MIC values for glyphosate and the glyphosate-containing product compared with isolates collected between 1981 and 1990. Isolates from pigs showed significantly higher MIC values
compared with isolates from poultry, and isolates of the Salmonella serovar Typhimurium had significantly higher
MIC values than Salmonella Enteritidis and Infantis isolates.
Enterococci are ubiquitous members of the human gut microbiota and frequent causes of biofilm-associated opportunistic infections. Enterococci cause 25% of all catheter-associated urinary tract infections, are frequently isolated in wounds and are increasingly found in infective endocarditis, and all of these infections are associated with biofilms. Enterococcal biofilms are intrinsically tolerant to antimicrobials and thus are a serious impediment for treating infections. In this Review, we describe the spatiotemporal development of enterococcal biofilms and the factors that promote or inhibit biofilm formation. We discuss how the environment, including the host and other co-colonizing microorganisms, affects biofilm development. Finally, we provide an overview of current and future interventions to limit enterococcal biofilm-associated infections. Overall, enterococcal biofilms remain a pressing clinical problem, and there is an urgent need to better understand their development and persistence and to identify novel treatments.
The increasing global emergence of multidrug-resistant (MDR) pathogens is categorized as one of the most important health problems. Therefore, the discovery of novel antimicrobials is of the utmost importance. Lichens provide a rich source of natural products including unique polyketides and polyphenols. Many of them display pharmaceutical benefits. The aim of this study was directed towards the characterization of sunflower oil extracts from the fruticose lichen, Usnea barbata. The concentration of the major polyketide, usnic acid, was 1.6 mg/mL extract as determined by NMR analysis of the crude mixture corresponding to 80 mg per g of the dried lichen. The total phenolics and flavonoids were determined by photometric assays as 4.4 mg/mL (gallic acid equivalent) and 0.27 mg/mL (rutin equivalent) corresponding to 220 mg/g and 13.7 mg/g lichen, respectively. Gram-positive (e.g., Enterococcus faecalis) and Gram-negative bacteria, as well as clinical isolates of infected chickens, were sensitive against these extracts as determined by agar diffusion tests. Most of these activities increased in the presence of zinc salts. The data suggest the potential usage of U. barbata extracts as natural additives and mild antibiotics in animal husbandry, especially against enterococcosis in poultry. View Full-Text
Keywords: usnic acid; Usnea barbata; Enterococcus faecalis; enterococcosis; natural antimicrobial; multidrug resistant bacteria; cytotoxicity; phenolics; flavonoids
Manure inputs into soil strongly affect soil microbial communities leading to shifts in microbial diversity and activity. It is still not clear whether these effects are caused mainly by the survival of microbes introduced with manure or by activation of the soil-borne microbiome. Here, we investigated how the soil microbiome was changed after the introduction of fresh farmyard cattle manure, and which microorganisms originating from manure survived in soil. Manure addition led to a strong increase in soil microbial biomass, gene copies abundances, respiration activity, and diversity. High-throughput sequencing analysis showed that higher microbial diversity in manured soil was caused mainly by activation of 113 soil-borne microbial genera which were mostly minor taxa in not-fertilized soil. Two weeks after manure input, 78% of the manure-associated genera were not detected anymore. Only 15 of 237 prokaryotic genera that originated from manure survived for 144 days in soil, and only 8 of them (primarily representatives of Clostridia class) were found in manured soil after winter. Thus, an increase in microbial biomass and diversity after manure input is caused mainly by activation of soil-borne microbial communities, while most exogenous microbes from manure do not survive in soil conditions after few months.
Environmental pollutants are present everywhere, in every breath and every bite, as well as in the air, food or water. These environmental pollutants may be natural or anthropogenic, and therefore this article focuses on pesticides, heavy metals or toxic dietary components. We will discuss the relationship between these pollutants and the gut microbiota and how it affects certain diseases, for example, through the gut-brain axis. At last, intestinal modulation with prebiotics or probiotics will be introduced under these environmental pollutants conditions.
Glyphosate-based herbicides are among the most used non-selective herbicides worldwide and inhibit synthesis of aromatic amino acids in plants, bacteria, and fungi. Given the broad usage, controversies concerning potential effects of glyphosate on health and especially on gut microbiomes arose. For cattle, it has been proposed based on in vitro data that glyphosate has detrimental effects on the ruminal microbiome, which manifest as a specific inhibition of bacteria involved in fiber degradation and as an enrichment of specific pathogens. In the present study, glyphosate effects on the ruminal microbiome were analyzed in vivo using glyphosate contaminated feedstuffs with strong differences in dietary fiber and dietary energy content in order to reproduce the proposed detrimental glyphosate effects on the rumen microbiome. While significant impact of dietary factors on the ruminal microbiome and its products are pointed out, no adverse glyphosate effects on ruminal microbiome composition, diversity, and microbial metabolites are observed.
Hawai'i's endangered waterbirds have experienced epizootics caused by ingestion of prey that accumulated a botulinum neurotoxin produced by the anaerobic bacterium Clostridium botulinum (avian botulism; Type C). Waterbird carcasses, necrophagous flies, and their larvae initiate and spread avian botulism, a food‐borne paralytic disease lethal to waterbirds. Each new carcass has potential to develop toxin‐accumulating necrophagous vectors amplifying outbreaks and killing hundreds of endangered waterbirds. Early carcass removal is an effective mitigation strategy for preventing avian intoxication, toxin concentration in necrophagous and secondary food webs, and reducing the magnitude of epizootics. However, rapid detection of carcasses can be problematic and labor intensive. Therefore, we tested a new method using scent detection canines for avian botulism surveillance on Kaua'i Island. During operational surveillance and a randomized double‐blind field trial, trained detector canines with experienced field handlers improved carcass detection probability, especially in dense vegetation. Detector canines could be combined with conventional surveillance to optimize search strategies for carcass removal and are a useful tool to reduce risks of the initiation and propagation of avian botulism.
Environmental monitoring of pesticide exposure is a key element of the holistic study of pesticides’ effects in human and animal health and the environment. The purpose of the current chapter is to present the existing methods for pesticide environmental monitoring, to give basic information on them, and to support the reader with a number of selected references for a more in-depth study of each one. Under the frame of the current chapter refers to exposure through open air, soil, water, and in-house environments meaning residences. In terms of environmental exposure and water, we refer to sea and freshwater, considering the potable water as part of the area of dietary exposure.
Pesticide impacts on the environment and humans are manifold. Due to the enormous variety of active ingredients with different mode of actions, no general patterns for the different pesticide classes can be identified. This chapter describes experiences from our own experiments and other studies testing pesticide effects on a variety of nontarget organisms, including soil biota, amphibians, insects, birds, and bats. If pesticides are applied at recommended doses, they are rarely acutely toxic to nontarget organisms. However, there are many indirect effects of pesticides on the activity, fitness, neurology, and reproduction of organisms. When a herbicide kills plants, this affects not only the diversity of the vegetation; the removal of nectar, pollen, food, and shelter for many insect pollinators, herbivores, birds, bats, and other mammals impairs overall biodiversity. A major problem is that environmental risk assessments of pesticides are only conducted for single active substances on a few surrogate species, thereby ignoring the agricultural practice with applications of many different pesticides during the cropping season, biodiversity, and ecological interactions in the agroecosystem. Side effects of pesticides on humans are worrying and include acute poisonings, and serious chronic diseases affecting the nerve system, the hormone system, interfering fertility, and reproduction, and can cause tumors. Morbus Parkinson is in some countries an occupational disease for winegrowers. Examples are mentioned where scientists who critically challenge the current use of pesticides were given a hard time.
Glyphosate, or N-phosphomethyl(glycine), is an organophosphorus compound and a competitive inhibitor of the shikimate pathway that allows aromatic amino acid biosynthesis in plants and microorganisms. Its utilization in broad-spectrum herbicides, such as RoundUp®, has continued to increase since 1974; glyphosate, as well as its primary metabolite aminomethylphosphonic acid, is measured in soils, water, plants, animals and food. In humans, glyphosate is detected in blood and urine, especially in exposed workers, and is excreted within a few days. It has long been regarded as harmless in animals, but growing literature has reported health risks associated with glyphosate and glyphosate-based herbicides. In 2017, the International Agency for Research on Cancer (IARC) classified glyphosate as “probably carcinogenic” in humans. However, other national agencies did not tighten their glyphosate restrictions and even prolonged authorizations of its use. There are also discrepancies between countries’ authorized levels, demonstrating an absence of a clear consensus on glyphosate to date. This review details the effects of glyphosate and glyphosate-based herbicides on fish and mammal health, focusing on the immune system. Increasing evidence shows that glyphosate and glyphosate-based herbicides exhibit cytotoxic and genotoxic effects, increase oxidative stress, disrupt the estrogen pathway, impair some cerebral functions, and allegedly correlate with some cancers. Glyphosate effects on the immune system appear to alter the complement cascade, phagocytic function, and lymphocyte responses, and increase the production of pro-inflammatory cytokines in fish. In mammals, including humans, glyphosate mainly has cytotoxic and genotoxic effects, causes inflammation, and affects lymphocyte functions and the interactions between microorganisms and the immune system. Importantly, even as many outcomes are still being debated, evidence points to a need for more studies to better decipher the risks from glyphosate and better regulation of its global utilization.
The increasing global emergence of multidrug resistant (MDR) pathogens is categorized as one of the most important health problems. Therefore, the discovery of novel antimicrobials is of the utmost importance. Lichens provide a rich source of natural products including unique polyketides and polyphenols. Many of them display pharmaceutical benefits. The aim of this study was directed towards the characterization of sunflower oil extracts from the fruticose lichen, Usnea barbata. The concentration of the major polyketide, usnic acid, was 1.6 mg/mL extract as determined by NMR analysis of the crude mixture corresponding to 80 mg per g of the dried lichen. The total phenolics and flavonoids were determined by photometric assays as 4.4 mg/mL (gallic acid equivalent) and 0.27 mg/mL (rutin equivalent) corresponding to 220 mg/g and 13.7 mg/g lichen, respectively. Gram-positive (e.g., Enterococcus faecalis) and Gram-negative bacteria, as well as clinical isolates of infected chickens were sensitive against these extracts as determined by agar diffusion tests. Most of these activities increased in the presence of zinc salts. The data suggest the potential usage of U. barbata extracts as natural additives and mild antibiotics in animal husbandry, especially against enterococcosis in poultry.
Three California juries have found that Monsanto should be liable for millions of dollars in non‐economic losses to pesticide users and punitive damages, although the verdicts are on appeal. The plaintiffs in the lawsuits claimed Monsanto was negligent in failing to provide training on how to use Roundup and for not providing adequate warnings about the product's dangers. The punitive damage awards resulted from jurors finding that the defendant had engaged in malice, oppression, or fraud. In June 2020, Monsanto's owner Bayer reached an agreement to resolve approximately 125,000 Roundup product liability claims for $10.1 billion. The verdicts and the proffered settlement suggest that pesticide products that unduly impair human health are not acceptable under American liability principles. Manufacturers need to design products that are reasonably safe and convey sufficient warning information to minimize damages to users and property. The placement of damage costs on product manufacturers is intended to encourage the development of safer pesticide products and the development of alternative non‐chemical pest‐control measures. This article is protected by copyright. All rights reserved
Despite an increasing concern of consequences of using vast amounts of glyphosate-based herbicides in agroecosystems, their potential effects on non-target soil organisms and soil functioning are mostly unknown. It has also been argued that fields in northern latitudes should be under special surveillance as the short active period of decomposers may restrict glyphosate degradation. We investigated the effects of a glyphosate-based herbicide, Roundup, on the abundance of enchytraeids and nematodes, both essential groups in decomposer food webs, and plant litter mass loss and soil availability of mineral N in a two-year agricultural field setting in south-west Finland. Our experiment consisted of (1) non-treated weed plots, (2) plots, where weeds were killed by hoeing, and (3) plots treated with both Roundup and hoeing. We found that killing plants by hoeing had drastic effects on soil fauna and functioning, and apparently, distinguishing these effects from direct glyphosate effects is profoundly important when evaluating glyphosate risks in soils. In contrast, the effects of Roundup on soil fauna and functioning were minor and transient and no glyphosate remains were found in the soil at the end of the experiment. These results suggest that side-effects can be minor and glyphosate degradation effective also in soil under northern climatic conditions.
The wide use of glyphosate-based herbicides (GBHs) has become a matter of concern due to its potential harmful effects on human health, including men fertility. This study sought to investigate, using the pig as a model, the impact of pure glyphosate and its most known commercial formulation, Roundup, on sperm function and survival. With this purpose, fresh commercial semen doses were incubated with different concentrations (0–360 µg/mL) of glyphosate (GLY; exp. 1) or Roundup, at the equivalent GLY concentration (exp. 2), at 38 °C for 3 h. Glyphosate at 360 µg/mL significantly (P < 0.05) decreased sperm motility, viability, mitochondrial activity and acrosome integrity but had no detrimental effect at lower doses. On the other hand, Roundup did significantly (P < 0.05) reduce sperm motility at ≥ 5 µg/mL GLY-equivalent concentration; mitochondrial activity at ≥ 25 µg/mL GLY-equivalent concentration; and sperm viability and acrosome integrity at ≥ 100 µg/mL GLY-equivalent concentration as early as 1 h of incubation. In a similar fashion, GLY and Roundup did not inflict any detrimental effect on sperm DNA integrity. Taken together, these data indicate that, while both glyphosate and Roundup exert a negative impact on male gametes, Roundup is more toxic than its main component, glyphosate.
Here we examined whether glyphosate affects the microbiota of herbivores feeding on non-target plants. Colorado potato beetles (Leptinotarsa decemlineata) were reared on potato plants grown in pots containing soil treated with glyphosate-based herbicide (GBH) or untreated. Per the manufacturer's safety recommendations, the GBH soil treatments were done two weeks prior to planting the potatoes. Later, two-day-old larvae were introduced to the potato plants and then collected in two phases, 4th instar larvae and adults. The larvae's internal microbiota and the adults' intestinal microbiota were examined by 16S rRNA gene sequencing. The beetles' microbial composition was affected by the GBH treatment and the differences in microbial composition between the control and insects exposed to GBH were more pronounced in the adults. The GBH treatment increased the relative abundance of Agrobacterium in the larvae and the adults. This effect may be related to the tolerance of some Agrobacterium species to glyphosate or to glyphosate-mediated changes in potato plants. On the other hand, the relative abundance of Enterobacteriaceae, Rhodobacter, Rhizobium and Acidovorax in the adult beetles and Ochrobactrum in the larvae were reduced in GBH treatment. These results demonstrate that glyphosate can impact microbial communities associated with herbivores feeding on non-target crop plants.
Genetic transformation in plants agreements a great potential to modify crops for improved agronomic traits including resistance to diseases, pests and good nutritional quality along with enhanced productivity. The transgene could be derived from unrelated plant species and even from non-plant sources leading to a revolution in molecular agriculture. In this chapter, the main approach lies on concept of genetic engineering techniques to improve the plant architect. The concept of GM crops and environmental implications besides their safety assessment is documented in detail and also in the end future perspective for adopting the next generation quantitative genetics is also elaborated.
Glyphosate is a non-selective systemic herbicide used in agriculture since 1974. It inhibits 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase, an enzyme in the shikimate pathway present in cells of plants and some microorganisms but not human or other animal cells. Glyphosate-tolerant crops have been commercialized for more than 20 years using a transgene from a resistant bacterial EPSP synthase that renders the crops insensitive to glyphosate. Much of the forage or grain from these crops are consumed by farm animals. Glyphosate protects crop yields, lowers the cost of feed production, and reduces CO2 emissions attributable to agriculture by reducing tillage and fuel usage. Despite these benefits and even though global regulatory agencies continue to reaffirm its safety, the public hears conflicting information about glyphosate’s safety. The US Environmental Protection Agency determines for every agricultural chemical a maximum daily allowable human exposure (called the reference dose, RfD). The RfD is based on amounts that are 1/100th (for sensitive populations) to 1/1000th (for children) the no observed adverse effects level (NOAEL) identified through a comprehensive battery of animal toxicology studies. Recent surveys for residues have indicated that amounts of glyphosate in food/feed are at or below established tolerances and actual intakes for humans or livestock are much lower than these conservative exposure limits. While the EPSP synthase of some bacteria is sensitive to glyphosate, in vivo or in vitro dynamic culture systems with mixed bacteria and media that resembles rumen digesta have not demonstrated an impact on microbial function from adding glyphosate. Moreover, one chemical characteristic of glyphosate cited as a reason for concern is that it is a tridentate chelating ligand for divalent and trivalent metals; however, other more potent chelators are ubiquitous in livestock diets, such as certain amino acids. Regulatory testing identifies potential hazards, but risks of these hazards need to be evaluated in the context of realistic exposures and conditions. Conclusions about safety should be based on empirical results within the limitations of model systems or experimental design. This review summarizes how pesticide residues, particularly glyphosate, in food and feed are quantified, and how their safety is determined by regulatory agencies to establish safe use levels.
There is growing recognition that the gut microbiome is an important regulator for neurological functions. This review provides a summary on the role of gut microbiota in various neurological disorders including neurotoxicity induced by environmental stressors such as drugs, environmental contaminants, and dietary factors. We propose that the gut microbiome remotely senses and regulates CNS signaling through the following mechanisms: 1) intestinal bacteria-mediated biotransformation of neurotoxicants that alters the neuro-reactivity of the parent compounds; 2) altered production of neuro-reactive microbial metabolites following exposure to certain environmental stressors; 3) bi-directional communication within the gut-brain axis to alter the intestinal barrier integrity; and 4) regulation of mucosal immune function. Distinct microbial metabolites may enter systemic circulation and epigenetically reprogram the expression of host genes in the CNS, regulating neuroinflammation, cell survival, or cell death. We will also review the current tools for the study of the gut-brain axis and provide some suggestions to move this field forward in the future.
Glyphosate (N-(phosphonomethyl)glycine) is the most-used herbicide worldwide. Many studies in the past have
shown that residues of the herbicide can be found in many cultivated plants, including those used as livestock feed.
Sensitivity to glyphosate varies with bacteria, particularly those residing in the intestine, where microbiota is exposed to glyphosate residues. Therefore, less susceptible pathogenic isolates could have a distinct advantage compared to more sensitive commensal isolates, probably leading to dysbiosis.
To determine whether the ruminal growth and survival of pathogenic Escherichia coli or Salmonella serovar Typhimurium are higher when glyphosate residues are present in the feed, an in vitro fermentation trial with a “Rumen
Simulation System” (RUSITEC) and a glyphosate-containing commercial formulation was performed.
Colony forming units of E. coli and Salmonella ser. Typhimurium decreased steadily in all fermenters, regardless
of the herbicide application. Minimum inhibitory concentrations of the studied Salmonella and E. coli strains did
not change, and antibiotic susceptibility varied only slightly but independent of the glyphosate application.
Overall, application of the glyphosate-containing formulation in a worst-case concentration of 10 mg/L neither increased the abundance for the tested E. coli and Salmonella strain in the in vitro fermentation system, nor promoted
resistance to glyphosate or antibiotics.
Biogas plants have been considered as a source for possible amplification and distribution of pathogenic bacteria capable of causing severe infections in humans and animals. Manure and biogas wastes could be sources for spore-forming bacteria such as Clostridium botulinum. In the present study, 24 liquid manure and 84 biogas waste samples from dairies where the majority of the cows suffered from chronic botulism were investigated for the presence of botulinum neurotoxins (BoNT) and C. botulinum spores. The prevalence of BoNT/A, B, C, D, and E in biogas wastes was 16.6, 8.3, 10.7, 7.1, and 10.8 %, respectively, while in manure, the prevalence was 0.0, 0.0, 0.0, 8.3, and 4.1 %, respectively. After enrichment of samples in reinforced cultural medium, they were tested for C. botulinum BoNT/A, B, C, D, and E using ELISA (indirect C. botulinum detection). The prevalence of C. botulinum type A, B, C, D, and E samples in biogas wastes was 20.2, 15.5, 19, 10.7, and 34.8 %, respectively, while the prevalence in liquid manure was 0.0, 0.0, 0.0, 8.3, and 12.5 %, respectively. In conclusion, the occurrence of BoNT and C. botulinum spores in biogas waste of diseased animals indicates an increased and underestimated hygienic risk. Application of digestates from biogas fermentations as fertilizers could lead to an accumulation of long lifespan spores in the environment and could be a possible health hazard.
Background:
Clostridium botulinum and related clostridial species express extremely potent neurotoxins known as botulinum neurotoxins (BoNTs) that cause long-lasting, potentially fatal intoxications in humans and other mammals. The amino acid variation within the BoNT is used to categorize the species into seven immunologically distinct BoNT serotypes (A-G) which are further divided into subtypes. The BoNTs are located within two generally conserved gene arrangements known as botulinum progenitor complexes which encode toxin-associated proteins involved in toxin stability and expression.
Methodology/principal findings:
Because serotype A and B strains are responsible for the vast majority of human botulism cases worldwide, the location, arrangement and sequences of genes from eight different toxin complexes representing four different BoNT/A subtypes (BoNT/A1-Ba4) and one BoNT/B1 strain were examined. The bivalent Ba4 strain contained both the BoNT/A4 and BoNT/bvB toxin clusters. The arrangements of the BoNT/A3 and BoNT/A4 subtypes differed from the BoNT/A1 strains and were similar to those of BoNT/A2. However, unlike the BoNT/A2 subtype, the toxin complex genes of BoNT/A3 and BoNT/A4 were found within large plasmids and not within the chromosome. In the Ba4 strain, both BoNT toxin clusters (A4 and bivalent B) were located within the same 270 kb plasmid, separated by 97 kb. Complete genomic sequencing of the BoNT/B1 strain also revealed that its toxin complex genes were located within a 149 kb plasmid and the BoNT/A3 complex is within a 267 kb plasmid.
Conclusions/significance:
Despite their size differences and the BoNT genes they contain, the three plasmids containing these toxin cluster genes share significant sequence identity. The presence of partial insertion sequence (IS) elements, evidence of recombination/gene duplication events, and the discovery of the BoNT/A3, BoNT/Ba4 and BoNT/B1 toxin complex genes within plasmids illustrate the different mechanisms by which these genes move among diverse genetic backgrounds of C. botulinum.
Current crop production relies heavily on transgenic, glyphosate-resistant (GR) cultivars. Widespread cultivation of transgenic crops has received considerable attention. Impacts of glyphosate on rhizosphere microorganisms and activities are reviewed based on published and new data from long-term field projects documenting effects of glyphosate applied to GR soybean and maize. Field studies conducted in Missouri, U.S.A. during 1997-2007 assessed effects of glyphosate applied to GR soybean and maize on root colonization and soil populations of Fusarium and selected rhizosphere bacteria. Frequency of root-colonizing Fusarium increased significantly after glyphosate application during growing seasons in each year at all sites. Roots of GR soybean and maize treated with glyphosate were heavily colonized by Fusarium compared to non-GR or GR cultivars not treated with glyphosate. Microbial groups and functions affected by glyphosate included Mn transformation and plant availability; phytopathogen-antagonistic bacterial interactions; and reduction in nodulation. Root-exuded glyphosate may serve as a nutrient source for fungi and stimulate propagule germination. The specific microbial indicator groups and processes were sensitive to impacts of GR crops and are part of an evolving framework in developing polyphasic microbial analyses for complete assessment of GR technology that is more reliable than single techniques or general microbial assays.
Repeated applications may have a greater impact on the soil microbial community than a single application of glyphosate. Experiments were conducted to study the effect of one, two, three, four or five applications of glyphosate on soil microbial community composition and glyphosate mineralization and distribution of (14)C residues in soil.
Fatty acid methyl esters (FAMEs) common to gram-negative bacteria were present in higher concentrations following five applications relative to one, two, three or four applications both 7 and 14 days after application (DAA). Additionally, sequencing of 16S rRNA bacterial genes indicated that the abundance of the gram-negative Burkholderia spp. was increased following the application of glyphosate. The cumulative percentage (14)C mineralized 14 DAA was reduced when glyphosate was applied 4 or 5 times relative to the amount of (14)C mineralized following one, two or three applications. Incorporation of (14)C residues into soil microbial biomass was greater following five glyphosate applications than following the first application 3 and 7 DAA.
These studies suggest that the changes in the dissipation or distribution of glyphosate following repeated applications of glyphosate may be related to shifts in the soil microbial community composition.
The bacteriocinogenicity of Lactococcus lactis ATCC 11454, Pediococcus pentosaceus ATCC 43200, P. pentosaceus ATCC 43201, Lactobacillus plantarum BN, L. plantarum LB592, L. plantarum LB75, and Lactobacillus acidophilus N2 against Clostridium botulinum spores at 4, 10, 15, and 35 degrees C was investigated by modified deferred and simultaneous antagonism methods. All the strains, except L. acidophilus N2, produced inhibition zones on lawns of C. botulinum spores at 30 degrees C. L. plantarum BN, L. lactis ATCC 11454, and P. pentosaceus ATCC 43200 and 43201 were bacteriocinogenic at 4, 10, and 15 degrees C. Supplementation of brain heart infusion agar with 0 to 5% NaCl increased the radii of inhibition zones during simultaneous antagonism assays. Detectable bacteriocin activities were extracted from freeze-thawed agar cultures of L. plantarum BN and L. lactis ATCC 11454 which had been grown at 4 and 10 degrees C. These results suggest that low levels of L. plantarum BN or L. lactis ATCC 11454, in the presence of 3 or 4% NaCl, could be formulated into minimally processed refrigerated food products for protection against possible botulism hazards.
Roundup is a glyphosate-based herbicide used worldwide, including on most genetically modified plants that have been designed to tolerate it. Its residues may thus enter the food chain, and glyphosate is found as a contaminant in rivers. Some agricultural workers using glyphosate have pregnancy problems, but its mechanism of action in mammals is questioned. Here we show that glyphosate is toxic to human placental JEG3 cells within 18 hr with concentrations lower than those found with agricultural use, and this effect increases with concentration and time or in the presence of Roundup adjuvants. Surprisingly, Roundup is always more toxic than its active ingredient. We tested the effects of glyphosate and Roundup at lower nontoxic concentrations on aromatase, the enzyme responsible for estrogen synthesis. The glyphosate-based herbicide disrupts aromatase activity and mRNA levels and interacts with the active site of the purified enzyme, but the effects of glyphosate are facilitated by the Roundup formulation in microsomes or in cell culture. We conclude that endocrine and toxic effects of Roundup, not just glyphosate, can be observed in mammals. We suggest that the presence of Roundup adjuvants enhances glyphosate bioavailability and/or bioaccumulation.
Clostridium botulinum neurotoxins (BoNTs) act on nerve endings to block acetylcholine release. Their potency is due to their enzymatic activity and selective high affinity binding to neurons. Although there are many pieces of data available on the receptor for BoNT, little attempt has been made to characterize the receptors for BoNT/C and BoNT/D. For this purpose, we prepared the recombinant carboxyl-terminal domain of the heavy chain (H(C)) and then examined its binding capability to rat brain synaptosomes treated with enzymes and heating. Synaptosomes treated with proteinase K or heating retained binding capability to both H(C)/C and H(C)/D, suggesting that a proteinaceous substance does not constitute the receptor component. We next performed a thin layer chromatography overlay assay of H(C) with a lipid extract of synaptosomes. Under physiological or higher ionic strengths, H(C)/C bound to gangliosides GD1b and GT1b. These data are in accord with results showing that neuraminidase and endoglycoceramidase treatment decreased H(C)/C binding to synaptosomes. On the other hand, H(C)/D interacted with phosphatidylethanolamine but not with any ganglioside. Using cerebellar granule cells obtained from GM3 synthase knock-out mice, we found that BoNT/C did not elicit a toxic effect but that BoNT/D still inhibited glutamate release to the same extent as in granule cells from wild type mice. These observations suggested that BoNT/C recognized GD1b and GT1b as functional receptors, whereas BoNT/D induced toxicity in a ganglioside-independent manner, possibly through binding to phosphatidylethanolamine. Our results provide novel insights into the receptor for clostridial neurotoxin.
Glyphosate [N-(phosphonomethyl) glycine]-resistant crops (GRCs), canola (Brassica napus L.), cotton (Gossypium hirsutum L.), maize (Zea mays L.), and soybean [Glycine max (L.) Merr.] have been commercialized and grown extensively in the Western Hemisphere and, to a lesser extent, elsewhere. Glyphosate-resistant cotton and soybean have become dominant in those countries where their planting is permitted. Effects of glyphosate on contamination of soil, water, and air are minimal, compared to some of the herbicides that they replace. No risks have been found with food or feed safety or nutritional value in products from currently available GRCs. Glyphosate-resistant crops have promoted the adoption of reduced- or no-tillage agriculture in the USA and Argentina, providing a substantial environmental benefit. Weed species in GRC fields have shifted to those that can more successfully withstand glyphosate and to those that avoid the time of its application. Three weed species have evolved resistance to glyphosate in GRCs. Glyphosate-resistant crops have greater potential to become problems as volunteer crops than do conventional crops. Glyphosate resistance transgenes have been found in fields of canola that are supposed to be non-transgenic. Under some circumstances, the largest risk of GRCs may be transgene flow (introgression) from GRCs to related species that might become problems in natural ecosystems. Glyphosate resistance transgenes themselves are highly unlikely to be a risk in wild plant populations, but when linked to transgenes that may impart fitness benefits outside of agriculture (e.g., insect resistance), natural ecosystems could be affected. The development and use of failsafe introgression barriers in crops with such linked genes is needed.
Levels of glyphosate were determined in water, soil and sediment samples from a transgenic soybean cultivation area located near to tributaries streams of the Pergamino-Arrecifes system in the north of the Province of Buenos Aires, Argentina. Field work took into account both the pesticide application and the rains occurring after applications. The pesticide was analysed by HPLC-UV detection, previous derivatization with 9-fluorenylmethylchloroformate (FMOC-Cl). In addition, SoilFug multimedia model was used to analyse the environmental distribution of the pesticides. In the field, levels of glyphosate in waters ranged from 0.10 to 0.70 mg/L, while in sediments and soils values were between 0.5 and 5.0 mg/Kg. Temporal variation of glyphosate levels depended directly on the time of application and the rain events. The results obtained from the application of the model are in accordance with the values found in the field.
Enterocin 1146, a bacteriocin produced by Enterococcus faecium. DPC1146, has a rapid bactericidal effect on Listeria in buffer systems, broth, and milk. In trypticase soy broth, increasing the bacteriocin dose and/or decreasing the pH extended the lag phase of Listeria innocua. A logarithmic relationship was found between response (as proportion of survivors or growth compared to a control) and dose. Increasing the inoculum level of the indicator reduced the effectiveness of enterocin 1146. Log-phase cells of L. innocua were more resistant than stationary-phase cells in both broth and buffer systems. In milk treated with 250 arbitrary units of enterocin 1146/ml and inoculated with 10³ or 10⁵ CFU/ml of Listeria monocytogenes Scott A, populations reached only 5-14% of the control after 24 h at 30°C, with numbers exceeding 10⁷, while at 6°C a slow decrease in population was found. Copyright ©, International Association of Milk, Food and Environmental Sanitarians.
Enterococcus faecium DPC 1146 produces a bacteriocin, enterocin 1146, which is inhibitory to Listeria monocytogenes. Enterocin 1146 was produced in GM17 and in milk. The bacteriocin was partially purified by ammonium sulfate precipitation. Its molecular weight, estimated by SDS-PAGE, was 3.0 kDa. It could be stored at -20°C without loss of activity, but pH had a marked effect on enterocin 1146, which was more stable at both high (up to 120°C) and low temperatures (4°C) at pH 5 than at pH 7 and 9. The sensitivity of 57 strains belonging to 35 different species was studied using a critical dilution assay. L. monocytogenes and L. innocua were most sensitive; enterocin 1146 had a bactericidal effect on Listeria. Starter and nonstarter lactic acid bacteria (except Lactobacillus sake) were insensitive or relatively resistant to the bacteriocin. Genetic determinants for bacteriocin production and immunity do not appear to be plasmid borne. Copyright ©, International Association of Milk, Food and Environmental Sanitarians.
Bacteriocins produced by lactic acid bacteria have a bactericidal effect against Gram-positive bacteria including foodborne pathogens such as Listeria monocytogenes, Bacillus cereus, and also inhibit the outgrowth of bacterial spores. Most of these bacteriocins are degradable in human tract, and heat stable, so that bacteriocins produced by lactic acid bacteria have potential use as natural food preservatives. Actually, nisin produced by the food-grade bacterium Lactococcus lactis is recognized as GRAS (Generally Recognized As Safe) substance and widely used as a preservative in the food industry. In recent years there has been a considerable increase in studies of bacteriocins produced by lactic acid bacteria not only on their structure, biosynthesis and mechanisms of pore-formation, but also on their potential applications as food preservatives. This review describes the current knowledge about the properties, biosynthesis, functional aspects, producer self-protection and resistance of a broad range of bacteriocins from lactic acid bacteria as well as the applications.
Pesticides constitute a major anthropogenic addition to natural communities. In aquatic communities, a great majority of pesticide impacts are determined from single-species experiments conducted under laboratory conditions. Although this is an essential protocol to rapidly identify the direct impacts of pesticides on organisms, it prevents an assessment of direct and indirect pesticide effects on organisms embedded in their natural ecological contexts. In this study, I examined the impact of four globally common pesticides (two insecticides, carbaryl [Sevin] and malathion; two herbicides, glyphosate [Roundup] and 2,4-D) on the biodiversity of aquatic communities containing algae and 25 species of animals.
Species richness was reduced by 15% with Sevin, 30% with malathion, and 22% with Roundup, whereas 2,4-D had no effect. Both insecticides reduced zooplankton diversity by eliminating cladocerans but not copepods (the latter increased in abundance). The insecticides also reduced the diversity and biomass of predatory insects and had an apparent indirect positive effect on several species of tadpoles, but had no effect on snails. The two herbicides had no effects on zooplankton, insect predators, or snails. Moreover, the herbicide 2,4-D had no effect on tadpoles. However, Roundup completely eliminated two species of tadpoles and nearly exterminated a third species, resulting in a 70% decline in the species richness of tadpoles. This study represents one of the most extensive experimental investigations of pesticide effects on aquatic communities and offers a comprehensive perspective on the impacts of pesticides when nontarget organisms are examined under ecologically relevant conditions.
The potent inhibition of the shikimate pathway enzyme 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase by the broad-spectrum herbicide glyphosate (N-[phosphonomethyl]glycine) was confirmed for the enzymes extracted from various bacteria, a green alga and higher plants. However, 5 out of 6 species belonging to the genus Pseudomonas were found to have EPSP synthases with a 50- to 100-fold decreased sensitivity to the inhibitor. Correspondingly, growth of these 5 species was not inhibited by 5 mM glyphosate, and the organisms did not excrete shikimate-3-phosphate in the presence of the herbicide.
Infant botulism results when Clostridium botulinum spores germinate, colonise, and produce botulinum neurotoxin in the intestine. As the normal intestinal microflora is important in resistance to C. botulinum colonisation in the mouse model of infant botulism, we investigated the effect of intestinal bacteria isolated from six healthy infants (two breastfed, two formula-fed, and two both formula and breast-fed) on the growth of 14 strains of C. botulinum (three Type A, four Type B, three Type E, two Type F, and two Type G) using zone inhibition procedures. We tested 88 anaerobic and 64 aerobic and facultative isolates. Strains of bifidobacteria, lactobacilli, propionibacteria and enterococci inhibited the growth of C. botulinum, as did several strains of the Bacteroides fragilis group. The only Clostridium inhibiting C. botulinum growth was C. ramosum, which inhibited both of the Type G strains and one of the two Type F strains. At least two bacterial isolates from each faecal sample inhibited most of the 14 C. botulinum strains. Co-culture experiments with intact faecal samples and C. botulinum spores or vegetative cells indicated that the normal flora of healthy infants had a bacteriostatic, rather than a bacteriocidal, effect on the growth of C. botulinum. Thus, susceptibility to infant botulism may result in part from the absence of these inhibitory organisms from the normal flora of the infant intestine.
N-Phosphonomethylglycine, a unique postemergence herbicide, appears to inhibit the aromatic amino acid biosynthetic pathway. The growth inhibition of Lemna gibba in the presence of this herbicide can be alleviated by the addition of L-phenylalanine to the nutrient medium. The growth inhibition of Rhizo-bium japonicum caused by N-phosphonpmethylglycine can only be alleviated by the addition of both L-phenylalanine and L-tyrosine. The data suggest that N-phosphonomethylglycine may inhibit or repress chorismate mutase and/or prephenate dehydratase.
The mobility in phloem of several substituted phosphonic acids and a sulfonic acid was studied in the castor bean plant, Ricinus communis L. For a series of14C-labelled phosphonate mono-esters applied to the petioles of mature leaves, phloem transport was modest, becoming poor over longer distances in the plant. Substituted phenylphosphonic acids were more efficiently moved in phloem; uptake from the petiole and subsequent redistribution were slow, but these dibasic compounds were very stable in plants and substantial amounts reached the roots after 72 to 120 h. Glyphosate was very efficiently transported to phloem sinks even within 24 h, with high concentrations in phloem sap. Toluene-4-sulfonic acid moved predominantly in the xylem to the mature leaves and its phloem transport was poor. Transport patterns are considered in relation to the physico-chemical properties of the compounds. Ion trapping appears to play little part in the phloem transport of these strong acids, though the good accumulation and transport in phloem of the complex molecule glyphosate cannot at present be explained.
Pesticides constitute a major anthropogenic addition to natural communities. In aquatic communities, a great majority of pesticide impacts are determined from single-species experiments conducted under laboratory conditions. Although this is an essential protocol to rapidly identify the direct impacts of pesticides on organisms, it prevents an assessment of direct and indirect pesticide effects on organisms embedded in their natural ecological contexts. In this study, I examined the impact of four globally common pesticides (two insecticides, carbaryl [Sevin] and malathion; two herbicides, glyphosate [Roundup] and 2,4-D) on the biodiversity of aquatic communities containing algae and 25 species of animals. Species richness was reduced by 15% with Sevin, 30% with malathion, and 22% with Roundup, whereas 2,4-D had no effect. Both insecticides reduced zooplankton diversity by eliminating cladocerans but not copepods (the latter increased in abundance). The in-secticides also reduced the diversity and biomass of predatory insects and had an apparent indirect positive effect on several species of tadpoles, but had no effect on snails. The two herbicides had no effects on zooplankton, insect predators, or snails. Moreover, the herbicide 2,4-D had no effect on tadpoles. However, Roundup completely eliminated two species of tadpoles and nearly exterminated a third species, resulting in a 70% decline in the species richness of tadpoles. This study represents one of the most extensive experimental inves-tigations of pesticide effects on aquatic communities and offers a comprehensive perspective on the impacts of pesticides when nontarget organisms are examined under ecologically relevant conditions.
The influence of the herbicide glyphosate on two-way interactions between four fungal species was investigated on agar using direct opposition, volatile inhibitor and non-volatile inhibitor tests, and on barley straw using tests for competitive saprotrophic ability. The results indicated that glyphosate was often capable of shifting the direction of two-species interactions, but there was little agreement between the different tests. Reanalysis of particle colonization data presented earlier demonstrated that glyphosate frequently eliminated negative associations between the same four species, possibly by acting as a resource. It is concluded that interactions between pairs of fungi can be influenced directly by glyphosate (especially at high concentrations) and that this may influence soil fungal community structure.
From 41 dairy farms in Schleswig Holstein, Germany, 196 fecal specimens of diseased cows, 77 fecal specimens of farmers and family members from 26 of these farms, 35 animal feed specimens and 7 house dust specimens were investigated for Clostridium botulinum and its antigens, respectively. Four of the humans under study (one child, 8 month, and three adults) showed symptoms of infant/visceral botulism. Specimens were cultivated in reinforced clostridial medium (RCM). C. botulinum antigens were detected by ELISA. The aim of the study was to obtain information on the relationship of detected C. botulinum toxin-types in cows, in the feces of attending humans, and in the immediate environment. The results revealed that C. botulinum toxin-types were different for cows and humans. Toxin-type A was dominant in cow feces while type E was found in humans. Type E was also present in some animal feed specimens. Conversely, toxin-type A was prevalent in the house dust of farms. It may be assumed that the feeds were the source of human colonization with C. botulinum.
Clostridia produce the highest number of toxins of any type of bacteria and are involved in severe diseases in humans and other animals. Most of the clostridial toxins are pore-forming toxins responsible for gangrenes and gastrointestinal diseases. Among them, perfringolysin has been extensively studied and it is the paradigm of the cholesterol-dependent cytolysins, whereas Clostridium perfringens epsilon-toxin and Clostridium septicum alpha-toxin, which are related to aerolysin, are the prototypes of clostridial toxins that form small pores. Other toxins active on the cell surface possess an enzymatic activity, such as phospholipase C and collagenase, and are involved in the degradation of specific cell-membrane or extracellular-matrix components. Three groups of clostridial toxins have the ability to enter cells: large clostridial glucosylating toxins, binary toxins and neurotoxins. The binary and large clostridial glucosylating toxins alter the actin cytoskeleton by enzymatically modifying the actin monomers and the regulatory proteins from the Rho family, respectively. Clostridial neurotoxins proteolyse key components of neuroexocytosis. Botulinum neurotoxins inhibit neurotransmission at neuromuscular junctions, whereas tetanus toxin targets the inhibitory interneurons of the CNS. The high potency of clostridial toxins results from their specific targets, which have an essential cellular function, and from the type of modification that they induce. In addition, clostridial toxins are useful pharmacological and biological tools.
Sixty soil samples were collected from the redeveloped site of the former Metropolitan (Caledonian) Cattle Market, Islington, London. Of these, 15 (25%) contained Clostridium botulinum and no less than four types (B, C, D and E) were demonstrated.
Early British soil surveys suggested that only 4–8% of samples contained Cl. botulinum (type A or B). Although there can be no absolute proof, it seems likely that the striking prevalence at the Market site was the result of faecal contamination by a small proportion of the many millions of farm animals brought there from elsewhere.
The distribution of Clostridium tetani was uneven, but of 18 soil samples taken from one area of the Market site, 16 (89%) were positive.
Conventional adult mice were pretreated with metronidazole to make their intestinal tracts receptive to colonization by Clostridium botulinum. These mice, in groups of 10, were fed 0 (controls), 10(2), 10(3), 10(4), or 10(5) C. botulinum type B spores and were placed for observation in filter-lid cages whose screen floors minimized the amounts of feces available for coprophagy. The opportunity to eat feces was made equal for all mouse groups by placing one mouse of every group in each of 10 cages. Mice given a spore inoculum began to develop botulism after incubation periods of slightly less than 2.75 days. Morbidity rates, which reached maxima within 5 days of challenge, were related to inocula levels. Mortality rates were also dose related. Mice given 10(5) spores and then type B antitoxin intraperitoneally, a treatment not affecting intraintestinal toxin production, remained healthy. Morbidity among control mice was seldom more than 10% and could be ascribed to toxin ingested with feces. A C. botulinum type A spore suspension gave similar results, although morbidity and mortality rates were generally lower than after challenge with a comparable number of type B spores. Mice challenged with 10(2) or 10(5) spores had similar toxin levels in their large intestines 48 h later. Morbidity rates correlated better with toxin levels in the small intestines.
The relationship between the indigenous intestinal microflora of adults and their resistance to the enteric botulinum infection of infant botulism was studied. Orogastric challenges of 10(5) type A Clostridium botulinum spores were given to adult mice whose gut flora had been altered by feedings of a mixture of erythromycin and kanamycin sulfate. From 80 to 100% of mice became infected when challenged 15 to 60 h after antibiotic administration. The mean infective dose of 2 X 10(4) spores per mouse for challenges given 23 h after antibiotic administration contrasted with the failure of 10(6) spores to infect control mice. Botulinum-colonized mice remained asymptomatic, although colonization lasted up to 5 days, and total botulinum toxin in the gut on days 3 and 4 postchallenge averaged 3,400 and 2,200 mouse intraperitoneal mean lethal doses. The mean infective dose for inocula placed in the colon of antibiotic-treated mice was 10(3) spores per mouse, and C. botulinum multiplied in the cecum as well as in the colon.
Lactic acid bacteria produce a variety of bacteriocins that have recently come under detailed investigation. The biochemical and genetic characteristics of these antimicrobial proteins are reviewed and common elements are discussed between the different classes of bacteriocins produced by these Gram-positive bacteria.
Nonproteolytic Clostridium botulinum (strains 17B, Beluga, and 202F) was found to be inhibited by Lactobacillus, Lactococcus, Streptococcus, and Pediococcus species in tests by the spot-on-the-lawn simultaneous-antagonism method at 10, 15, and 25 degrees C. C. botulinum 17B was the most resistant strain. Inhibition zone size increased with decreasing incubation temperature. Six strains of Lactobacillus acidophilus and seven strains of bifidobacteria failed to produce an inhibition zone on buffered reinforced clostridium Prussian blue agar seeded with spores of any of the selected C. botulinum strains. C. botulinum 17B was sensitive to 50 to 100 IU of nisin per ml and to 10 to 20 AU of pediocin A per ml.
Botulinum toxin is a uniquely potent substance synthesized by the organisms Clostridium botulinum, Clostridium baratii, and Clostridium butyricum. This toxin, which acts preferentially on peripheral cholinergic nerve endings to block acetylcholine release, is both an agent that causes disease (i.e., botulism) as well as an agent that can be used to treat disease (e.g., dystonia). The ability of botulinum toxin to produce its effects is largely dependent on its ability to penetrate cellular and intracellular membranes. Thus, toxin that is ingested or inhaled can bind to epithelial cells and be transported to the general circulation. Toxin that reaches peripheral nerve endings binds to the cell surface then penetrates the plasma membrane by receptor-mediated endocytosis and the endosome membrane by pH-induced translocation. Internalized toxin acts in the cytosol as a metalloendoprotease to cleave polypeptides that are essential for exocytosis. This review seeks to identify and characterize all major steps in toxin action, from initial absorption to eventual paralysis of cholinergic transmission.
Binding of Clostridium botulinum type C and D neurotoxins to ganglioside and phospholipid. Novel insights into the receptor for clostridial neurotoxin
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Probiotics: a general view in lactic acid bacteria
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