Article

Antimicrobial Activity of Sodium Bicarbonate

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Abstract

Sodium bicarbonate (SB) inhibited the growth of bacteria and yeasts in agar media model systems under certain conditions. Escherichia coli, Lactobacillus plantarum, Staphylococcus aureus, and Pseudomonas aeruginosa aerobic plate counts were reduced 10,000-fold by 0.12M (1% w/v) SB. Saccharomyces cerevisiae and Hansenula wingei were more sensitive; counts were reduced 100,000-fold by 0.06M SB. Potassium bicarbonate was equally inhibitory, but equimolar sodium chloride had no effect, ruling out osmotic- and sodium-mediated mechanisms of inhibition. The bicarbonate ion was identified as the probable cause of SB-mediated inhibition although, in some cases, pH elevation played a significant role.

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... These inhibitory effects were observed following both 6-and 17-h incubations, indicating that bacterial growth was hampered both in exponential and stationary phases. These findings are in accordance with previous observations demonstrating the antimicrobial effects of NaHCO 3 [19,[31][32][33]. Corral and colleagues reported that 120 mM NaHCO 3 reduces the CFU counts of E. coli, L. plantarum, S. aureus and P. aeruginosa 10,000-fold. ...
... Corral and colleagues reported that 120 mM NaHCO 3 reduces the CFU counts of E. coli, L. plantarum, S. aureus and P. aeruginosa 10,000-fold. This effect is more pronounced in yeasts such as S. cerevisiae and H. wingei, with 100,000-fold growth reductions induced by 60 mM NaHCO 3 [31]. More recently, it has been demonstrated that NaHCO 3 has antimicrobial effects on E. coli when applied in concentrations higher than 25 mM [32]. ...
Article
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Cystic fibrosis (CF) is a hereditary disease caused by mutations in the gene encoding an epithelial anion channel. In CF, Cl− and HCO3− hyposecretion, together with mucin hypersecretion, leads to airway dehydration and production of viscous mucus. This habitat is ideal for colonization by pathogenic bacteria. We have recently demonstrated that HCO3− inhibits the growth and biofilm formation of Pseudomonas aeruginosa and Staphylococcus aureus when tested in laboratory culture media. Using the same bacteria our aim was to investigate the effects of HCO3− in artificial sputum medium (ASM), whose composition resembles CF mucus. Control ASM containing no NaHCO3 was incubated in ambient air (pH 7.4 or 8.0). ASM containing NaHCO3 (25 and 100 mM) was incubated in 5% CO2 (pH 7.4 and 8.0, respectively). Viable P. aeruginosa and S. aureus cells were counted by colony-forming unit assay and flow cytometry after 6 h and 17 h of incubation. Biofilm formation was assessed after 48 h. The data show that HCO3− significantly decreased viable cell counts and biofilm formation in a concentration-dependent manner. These effects were due neither to extracellular alkalinization nor to altered osmolarity. These results show that HCO3− exerts direct antibacterial and antibiofilm effects on prevalent CF bacteria.
... The compound exhibited inhibitory properties towards microbial growth and biofilm formation [15]. Corral (1988) [16] concluded that the sodium bicarbonate inhibition occurs from the release of bicarbonate ion and the resulting pH instability. Interestingly, in both of these literatures Pseudomonas aeruginosa was among the selection of microbes tested against the compound. ...
... The compound exhibited inhibitory properties towards microbial growth and biofilm formation [15]. Corral (1988) [16] concluded that the sodium bicarbonate inhibition occurs from the release of bicarbonate ion and the resulting pH instability. Interestingly, in both of these literatures Pseudomonas aeruginosa was among the selection of microbes tested against the compound. ...
Conference Paper
Nitrate (NO3⁻) is one of the most common targets for water quality control. High nitrate concentration in the water systems negatively impact human health and the environment. Excessive nitrate content in the aquatic environment led to a decrease in water quality, which can be evaluated from changes in color, odor, increased turbidity, and reduced levels of dissolved oxygen. Denitrification as a biological method of tackling nitrate pollution has been studied since three decades ago in various systems, including recent investigations into bioelectrochemical systems. Bioelectrochemical cells are driven by microorganisms in carrying out oxidation/reduction reactions such as denitrification. However, the popularity of BES is still low. This study aim to optimize the source of carbon as substrate in culture media for the system and compare the efficiency of nitrate elimination and denitrification rate among isolates and culture conditions. Axenic cultures of Pseudomonas entomophila and Acinetobacter oleivorans were done in 20 mL single-chambered Microbial Electrolysis Cells (MECs) equipped with graphite as anode and stainless steel mesh as cathode. Sodium acetate and sodium bicarbonate was used as carbon sources in the formulation of heterotrophic and mixotrophic media. Denitrification performance in bioelectrochemical cells was evaluated from the evolution of nitrate concentration in the medium and the growth of target microorganisms. Environmental isolates presented similar behavior on the medium supplemented with bicarbonate by reaching 68-69% maximum nitrate removal efficiency across all experiments, suggesting inability to carry out autotrophic denitrification. On the other hand, Pseudomonas aeruginosa reached 78% efficiency on acetate-only medium, suggesting a preference towards acetate as carbon source over bicarbonate. Environmental isolates presented an interesting potential of tolerating the potential inhibitory effects of sodium bicarbonate in the medium compared to Pseudomonas aeruginosa, which demonstrated inhibitory effects in this medium.
... Gutiérrez-Huante et al., (2019) revealed that iron deficiency may also be involved in the inhibition of bacterial growth by NaHCO 3 (Gutiérrez-Huante et al., 2019). However, in some cases, pH elevation also played a significant role (Corral et al., 1988). Scientists have found that the virucidal efficacy of NaHCO 3 was also enhanced when it was used in combination with aldehydes or hydrogen peroxide (Malik and Goyal, 2005). ...
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Objective Surgical face masks have been recommended by World Health Organization (WHO) during the COVID-19 pandemic. Nowadays wearing masks have become a norm and lifestyle around the globe. The present investigation was carried out to evaluate the feasibility of developing masks loaded with analytical grade sodium chloride (NaCl), Iodized salts (IS) and Omani sea salt (OSS) with or without sodium bicarbonate (NaHCO3). Methods The saline loaded masks were prepared by soaking the middle layer of the mask in 30 % (w/v) saline solutions (NaCl, IS, OSS) with or without 10% NaHCO3 for 24 hours followed by drying at room temperature. The prepared saline solutions and its combinations were evaluated for antimicrobial efficacy against the bacteria like Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Salmonella typhi, and Staphylococcus aureus, and antifungal activity against the Penicillium spp and Rhizopus spp by agar diffusion. Optical microscopy was employed to observe the formation of salt crystal in the mask material. Survivability of S. aureus and P. aeruginosa was tested on the mask material loaded with 30% OSS+10% NaHCO3 at particular time intervals. Results The results showed that a combination of 30% OSS+10% NaHCO3 exhibited promising antimicrobial activity against all the bacteria as well as Rhizopus spp compared to the 30% IS+10% NaHCO3. Moreover, the middle layer of the mask loaded with saline solutions of 30% OSS+10% NaHCO3 or 30% IS+10% NaHCO3 have antibacterial activity, particularly for oral microbiome. On dehydration, the masks materials showed the presence of a significant amount of salt crystals. Survivability tests showed that both S. aureus and P. aeruginosa were killed within 3 hours of contact with the salt crystals on the mask materials. Conclusions A combination of 30% OSS+10% NaHCO3 possessed significant antimicrobial activities on the tested microorganisms. Presence of a significant amount of salt crystals on dehydration of the saline loaded masks can be used as an effective protective barrier to infectious respiratory agents.
... This decrease was accompanied by increasing the reduction of disease severity and number of colonies. This may be due to the antibacterial activity of baking soda and potassium which inhibited the growth of bacteria and fungi (Corral et al., 1988 andDrake, 1996). Reversely, in curative treatment, the squash leaves treated with potassium and sodium bicarbonate showed a significant increase in the number of total count in the three cultivars when compared to control and this increase was accompanied by significant increase in the reduction of disease severity and number of colonies. ...
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Foliar applications of potassium or sodium bicarbonate salts significantly reduced infection by powdery mildew on greenhouse squash. Application of compost-tea and sodium or potassium bicarbonate solutions to squash plants, either as protective or as curative treatments, significantly reduced powdery mildew infection. Different foliar applications, when applied as protective (pre-inoculation) treatments, three days before inoculation, reduced severity of powdery mildew except compost-tea (1kg/4L water). Application of sodium bicarbonate solution at 2% was the most effective treatment, which reduced disease severity and number of mildew colonies by 80.0 and 93.1%, respectively, followed by application of potassium bicarbonate. Meanwhile, compost-tea (1kg/6L water) treatment recorded the maximum value for total bacterial count (84.8 x10 3 cfu). Generally, squash leaves treated with KHCO3 and NaHCO3 showed a significant decrease in the number of total bacterial count and total spore forming bacteria on the three tested cultivars when compared to untreated control. Application of compost-tea or bicarbonate salts as curative (post-inoculation) treatment, three days after fungal inoculation, caused marked reduction in disease severity. However, the treatment with the lower rate of compost-tea (1kg/4L water) showed the highest curative activity and reduced disease severity and number of colonies significantly. On the other hand, the maximum value for total bacterial count was obtained when squash Eskandarani Hybrid was sprayed with NaHCO3 followed by compost-tea (1kg/8L water) whereas it recorded (745.0 x 10 3 cfu) and (560.0 x 10 3 cfu), respectively. The application of various treatments, either as protective or as curative, enhanced peroxidase activity in treated plants. However, foliar spray for the three squash varieties with sodium or potassium bicarbonate solutions showed the highest increase in the peroxidase activity compared to the untreated infected or not infected control as well as compost-tea treatments. Under field conditions, spraying squash plants with different solutions , 30 and 60 days after sowing reduced severity of powdery mildew while, the total fruit yield was improved. However, application with 2% of potassium bicarbonate (KHCO 3) solution was the best treatment, which significantly increased squash yield of all treated varieties compared to the untreated control, followed by
... Based on this composition, a series of extenders have come on the market, mostly spiked with sperm membrane protecting agents and additional powerful buffers to achieve long-term preservability up to 7 d [20]. Basic semen extender components, like EDTA and bicarbonate, are known to be antimicrobially effective, alone or in synergism with antimicrobial agents [21,22]. Although extender ingredients are no longer published, it is reasonable to hypothesise that antibiotic-free semen extenders differ in their intrinsic antimicrobial capacity. ...
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Antibiotic use in semen extenders for livestock may contribute to the development and spreading of multi-drug resistance. Antimicrobial control in semen doses for artificial insemination of pigs is indispensable due to the relatively high storage temperature (17 °C). The objectives of this study were first, to examine whether the antimicrobial capacity differs between antibiotic-free extenders and second, to determine whether an antimicrobial active extender provides the possibility to reduce antibiotics. Antibiotic-free semen extenders Beltsville Thawing Solution (BTS) and Androstar Premium were inoculated at 103 to 104 CFU/mL with four pure bacterial strains isolated from boar ejaculates or a mixture thereof, and then stored for 144 h at 17 °C. Bacterial counts after aerobic culture decreased in BTS up to one log level and decreased in Androstar Premium by 2 to 3.5 log levels (p < 0.05). In semen samples from nine boars stored in the inoculated Androstar Premium extender containing half of the standard concentration of gentamicin, bacteria counts were below 101 CFU/mL. Likewise, half of the standard dose of apramycin and ampicillin was fully antimicrobially active and sperm quality was maintained. In conclusion, semen extenders with intrinsic antimicrobial activity allow a reduction in antibiotic use in pig insemination.
... Even though AST of fungi uses RPMI-1640 liquid medium, a mammalian cell culture medium, this is buffered to pH 7.0 with MOPS (CLSI, 2017a,c), rather than sodium bicarbonate as it would be when culturing mammalian cells and using a CO 2 incubator (5% CO 2 ). Sodium bicarbonate has antibacterial, antifungal and antibiofilm properties of its own, but only at supra-physiological concentrations (≥50 mM) (Corral et al., 1988;Xie et al., 2010;Letscher-Bru et al., 2013;Dobay et al., 2018;Farha et al., 2018). Bicarbonate acts as a selective dissipater of the trans-membrane pH gradient, a component of the proton motive force (along with the membrane potential) and can enhance the activity of AMP, including LL-37, α-defensin, indolicidin, protegrin and bactenecin and selected antibiotics, including aminoglycosides, macrolides and selected fluoroquinolones. ...
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During the development of antimicrobial peptides (AMP) as potential therapeutics, antimicrobial susceptibility testing (AST) stands as an essential part of the process in identification and optimisation of candidate AMP. Standard methods for AST, developed almost 60 years ago for testing conventional antibiotics, are not necessarily fit for purpose when it comes to determining the susceptibility of microorganisms to AMP. Without careful consideration of the parameters comprising AST there is a risk of failing to identify novel antimicrobials at a time when antimicrobial resistance (AMR) is leading the planet toward a post-antibiotic era. More physiologically/clinically relevant AST will allow better determination of the preclinical activity of drug candidates and allow the identification of lead compounds. An important consideration is the efficacy of AMP in biological matrices replicating sites of infection, e.g., blood/plasma/serum, lung bronchiolar lavage fluid/sputum, urine, biofilms, etc., as this will likely be more predictive of clinical efficacy. Additionally, specific AST for different target microorganisms may help to better predict efficacy of AMP in specific infections. In this manuscript, we describe what we believe are the key considerations for AST of AMP and hope that this information can better guide the preclinical development of AMP toward becoming a new generation of urgently needed antimicrobials.
... Slightly hypotonic, 1% solution, can be used as a mild mouthwash to neutralise acids, moisturise, deodorise and decrease the number of bacteria [84]. A hypertonic solution of sodium bicarbonate facilitates osmotic movement of water from bacterial cells, resulting in shrinkage, plasmolysis and cell death [93]. Sodium bicarbonate in solution is able to disrupt biofilms without an antimicrobial effect, hypothetically by disrupting the exopolysaccharide matrix structure of dental plaque [94]. ...
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Mouthwashes are a very popular additional oral hygiene element and there are plenty of individual products, whose compositions are in a state of flux. The aim of our study was to investigate the compositions of mouthwashes and their functions, as well as to discuss their effectiveness in preventing and curing oral diseases and side effects. We searched for mouthwashes available on the market in Poland. We identified 241 individual mouthwash products. The extraction of compositions was performed and functions of the ingredients were assessed. Then, analysis was performed. The evaluation revealed that there are plenty of ingredients, but a typical mouthwash is a water–glycerine mixture and consists of additional sweetener, surfactant, preservative, and some colourant and flavouring agent, as well as usually having two oral health substances, anticaries sodium fluoride and antimicrobial essential oils. The effectiveness or side effects of several substances of mouthwashes were thoroughly discussed. We recommend not multiplying individual mouthwash products and their ingredients beyond medical or pharmaceutical necessity, especially without scientific proof.
... These issues have resulted in an intensive search for non polluting control methods. Various alternative measures such as the application of microorganisms (El-Ghaouth et al., 2000; Lahlali et al., 2011; Taqarort et al., 2008), plant extracts (Ameziane et al., 2007; Askarne et al., 2013) or the use of effective natural substances like food additives that have minimal adverse effect on the environment and health (Arslan et al., 2009) and which exhibit a broad-spectrum antifungal activity (Corral et al., 1988), in combination or in a replacement for fungicide have been developed . Several studies have dealt with the use of different salt compounds to control various post-harvest diseases of citrus and other crops (Arslan et al., 2006; Arslan et al., 2009; Nigro et al., 2006). ...
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The aim of this study was to find an alternative to the chemical fungicide currently used in the control of postharvest citrus diseases. The antifungal activity of 10 salt compounds, considered as common food additives was assayed in in vitro and in vivo trials against Penicillium italicum, causal agent of citrus blue mold. Among the 10 tested salt compounds, sodium carbonate, ammonium carbonate, copper sulfate, sodium EDTA and sodium metabisulfite completely inhibited mycelial growth of Penicillium italicum at 20 mM. Colony growth of P. italicum on pH adjusted medium was evaluated. Results indicate that P. italicum can grow on both acidic and alkaline pH, with the optimum growth occurred in the range of 4.0 and 8.0. Results of the in vivo trials with tested salt compounds indicate that sodium metabisulfite (100 and 200 mM), boric acid (400 mM), sodium salicylate and sodium sulfite (200, 300 and 400 mM) completely inhibited blue mold development on citrus fruit. Boric acid (400 mM) and sodium metabisulfite (100 mM) gave the best results as they completely inhibited the fungus development without damaging fruit rind. Such healthy products therefore may represent a sustainable alternative to the use of chemical fungicides for controlling postharvest diseases of citrus fruit.
... Taken together, HCO3− may exert its bactericidal effect by acting on sAC to induce increase in cAMP production, which in turn suppresses protein synthesis and thus reduces the viability of bacteria. While most previous studies have implicated HCO3− in bacterial killing either by altering pH [64] or increase the susceptibility of bacteria to antimicrobial peptides [46]. In the present study, we have demonstrated a direct bacterial killing effect of HCO3− through cAMP dependent pathway. ...
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Prostatitis is associated with a characteristic increase in prostatic fluid pH; however, the underlying mechanism and its physiological significance have not been elucidated. In this study a primary culture of rat prostatic epithelial cells and a rat prostatitis model were used. Here we reported the involvement of CFTR, a cAMP-activated anion channel conducting both Cl(-) and HCO(3)(-), in mediating prostate HCO(3)(-) secretion and its possible role in bacterial killing. Upon Escherichia coli (E. coli)-LPS challenge, the expression of CFTR and carbonic anhydrase II (CA II), along with several pro-inflammatory cytokines was up-regulated in the primary culture of rat prostate epithelial cells. Inhibiting CFTR function in vitro or in vivo resulted in reduced bacterial killing by prostate epithelial cells or the prostate. High HCO(3)(-) content (>50 mM), rather than alkaline pH, was found to be responsible for bacterial killing. The direct action of HCO(3)(-) on bacterial killing was confirmed by its ability to increase cAMP production and suppress bacterial initiation factors in E. coli. The relevance of the CFTR-mediated HCO(3)(-) secretion in humans was demonstrated by the upregulated expression of CFTR and CAII in human prostatitis tissues. The CFTR and its mediated HCO(3)(-) secretion may be up-regulated in prostatitis as a host defense mechanism.
... Bicarbonate salts enhance the textural quality of meat products by improving product juiciness, overall palatability, reduced drip-loss, and shear force (Kauffman et al., 1998;Sheard & Tali, 2004;Wynveen et al., 2001b;Sen et al., 2005a;Lee, Sharma, Brown, & Mohan, 2015). NaHCO 3 is a GRAS (generally recognized as safe) food ingredient used as a leavening agent, to control pH, as an antimicrobial, and to improve taste, texture, and tenderness characteristics (Corral, Post, & Montville, 1988;Curran & Montville, 1989;Bechtel, Oreskovich, McKeith, Martin, & Novakofski, 1989;Lee, Sharma, Brown, & Mohan, 2015). ...
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Whole chicken breast was injected with potassium bicarbonate (PB), sodium bicarbonate (SB), and potassium lactate (K-lactate) and salt, alone or in combination at different concentration levels. The objectives were to 1) investigate the effects of different concentration of PB, SB, and PL on instrumental color, water-holding capacity (WHC), objective tenderness, expressible moisture, and moisture content and 2) evaluate whether sodium-containing ingredients can be replaced with potassium as a potential strategy to reduce total sodium content in the finished product. Results showed that chicken breast tissue marinated with SB and PB had greater moisture retention, display characteristics, and cooked product qualities than chicken breast tissue injected with water and the nonmarinated control. The L* values (lightness) did not change over the period of retail display and were not different compared to the control (P > 0.05). The chicken breast enhanced with SB, PB, and K-lactate retained better retail display color than the controls (marinated with water and nonmarinated). Increasing the potassium bicarbonate concentration from 0.5 to 1.5% significantly improved the water-holding capacity (82.17 to 92.61%; P < 0.05) and led to better cook yield (83.84 to 91.96%). Shear force values were lower at the 0.5% level for both SB and PB compared to the control. PB performed better on retail display and cooked meat quality than SB. This study suggests that chicken breast tissue can be marinated with KB as a healthier alternative to phosphate or SB.
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The aim of this study was to find an alternative to the chemical fungicide currently used in the control of postharvest citrus sour rot. Here we screened thirty-two salt compounds, considered as common food additives, for their activity against Geotrichum candidum, causal agent of citrus sour rot. The lowest Minimum Inhibitory Concentrations (MECs) values were obtained by ammonium carbonate and EDTA at a concentration of 0.1% (w/v) and boric acid, sodium carbonate and sodium metabisulfite at 0.25% (w/v). Over all, the medium-pH in the range of 4.0 to 12.0 did not influence the mycelial growth of the pathogen. The ten best salt compounds were tested for their ability to reduce the arthrospores germination of the fungus. The effect of salts varied significantly (p<0.05) between tested compounds and depended on their concentrations. The arthrospore germination was completely inhibited by EDTA, boric acid, sodium metabisulfite, sodium carbonate, sodium sulfate and sodium thiosulfate, both at 100 and 75 mM. The most active salts in in vitro studies were tested in vivo against sour rot on citrus fruit. Incidence of sour rot was lowered to 25.93 and 38.89%, when mandarin fruit where treated by sodium salicylate, boric acid and EDTA, compared with 100% in the control. However, only the application of boric acid at 3% (w/v) reduced disease severity by more than 70%. These results suggest that sodium salicylate, boric acid and EDTA may be useful and effective compounds for control of citrus sour rot. Such healthy products therefore represent a sustainable alternative to the use of guazatine mainly in organic production.
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In this work different packaging strategies aimed to prolong the shelf life of minimally processed zucchini are presented. In particular, two different cultivars (Sofia and Diamante) were tested. The sliced zucchini were packaged in oriented polypropylene-based (OPP) bag and into a bio-polymeric film (COEX) under passive and active MAP. The investigated produce was stored at 5°C for approximately 9days. Headspace gas concentrations, pH, mass loss, sensory quality and viable cell load of main spoilage microorganisms were monitored for the entire observation period. In order to determine the respiration activity, O2 and CO2 concentrations were monitored not only in OPP and COEX packages but also in the headspace of an aluminum-based package. Results suggested that for Diamante cultivar OPP film under active and passive MAP showed slightly better performances in prolonging the shelf life, compared to COEX film; instead, for Sofia cultivar better results were obtained with OPP film only under active MAP conditions.
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An integrated approach using hot water treatment (HWT) and salt in the control of crown rot disease and preservation of quality in banana was investigated. The efficacy of HWT and either sodium carbonate (SC), sodium bicarbonate (SBC) or sodium hypochlorite (SH) applied alone or in combinations was evaluated against cultures of Lasiodiplodia theobromae, Thielaviopsis paradoxa, Colletotrichum musae and Fusarium verticillioides. The in vitro efficacy of salt was enhanced by 36.85–62.05% following HWT. Postharvest application, involving fruit dipped for 30 min in 1% (w/v) SC following HWT (50°C, 20 min), and storage for 14 d at 22–25ºC and 90–95% relative humidity, maintained the overall quality of bananas and reduced the incidence of crown rot by 87.99%, which was comparable with that of treatment with fungicide at 89.60%. Other treatment combinations were capable of reducing crown rot to a lesser extent such as 80.64% by HWT + SH and 77.59% by HWT + SBC. Individual treatments were significantly lower at 70.07% for SH, 64.32% for SC, and 59.67% for SBC. HWT alone showed the lowest efficacy in controlling fruit decay at 52.15%.
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We explored feasibility of wafer-scale two-dimensional (2D) molybdenum disulfide (MoS2) layers towards futuristic environmentally-friendly electronics that adopt biodegradable substrates. Large-area (> a few cm2) 2D MoS2 layers grown on SiO2/Si wafers were delaminated and integrated onto a variety of cellulose-based substrates of various components and shapes in a controlled manner; examples of the substrates include planar papers, cylindrical natural rubbers, and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOCNs). The integrated 2D layers were confirmed to well preserve their intrinsic structural and chemical integrity, even on such exotic substrates. Proof-of-concept devices employing large-area 2D MoS2 layers/cellulose substrates were demonstrated for a variety of applications, including photodetectors, pressure sensors, and field-effect transistors (FETs). Furthermore, we demonstrated the complete “dissolution” of the integrated 2D MoS2 layers in a buffer solution composed of baking soda and deionized (DI) water, confirming their environmentally-friendly transient characteristics. Moreover, the approaches to delaminate and integrate them do not demand any chemicals except for water, and their original substrates can be recycled for subsequent growths, ensuring excellent chemical benignity and process sustainability.
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In this long-term field study, to restore a dried river ecosystem, reclaimed water was used as a supplementary water source. The main aim of this study was to investigate the accumulation and migration potential of EDCs in groundwater during long-term utilization of reclaimed water and the changes in microbial community during the removal of EDCs. A long-term field study was conducted in order to ascertain the temporal and spatial distribution of four selected endocrine-disrupting chemicals (EDCs) in an underground aquifer in the Chaobai watershed, where reclaimed water is the primary water source. Anew, the microbial community structure at different groundwater depths, along with related environmental factors were also determined. Based on the results obtained from this long-term study, it was found that the EDCs in the surface water of the Chaobai river have entered a depth of 80 m in the groundwater aquifers, within a distance of 360 m from the river. The vertical profiles of the concentrations of bisphenol A (BPA), 4-nonylphenol (NP), estrone (E1), and estriol (E3) decreased significantly from the surface to different groundwater depths with first-order attenuation rates of 0.0416, 0.0343, 0.0498, and 0.0173 m-1. The aquifer depth, water temperature, conductivity, and coexisting anions correlated well with the distribution of EDCs in groundwater.
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This work investigates preparation by extrusion of microcellular antimicrobial polylactide (PLA) with an additive, the latter comprising 1% potassium aluminum sulfate dodecahydrate (ALUM), and 3% or 5% of a mixture of sodium hydrogen carbonate and sodium dihydrogen phosphate (1:1). Study was made as to the properties of the materials, their hydrolysis, release profiles, and antimicrobial properties in comparison with the pure polymer. Measuring the molecular weight of samples by gel permeation chromatography revealed that, during thermal processing, the molecular weight of the PLA prepared with additives mentiond above had reduced by approximately 43%. A mechanical test confirmed a decline in mechanical properties after processing as compared with the pure PLA. Release of the antimicrobial compound and the subsequent antimicrobial activity against Staphylococcus aureus and Escherichia coli was evaluated according to ISO 22196:2007. The release of ALUM from the microcellular specimens took place in two steps. During the first 10 days, the rate of release was extremely high in contrast with the remaining period. However, the release rate of the nonporous sample was seen to equal less than 1% in the first 10 days, a phenomenon probably arising through its less active surface.
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Hazelnut (Corylus avellana L.) which is intensively grown in the Black Sea region is the most important agricultural product of Turkey. Hazelnut production and quality are negatively affected by several diseases and pests. Powdery mildew is nowadays one of the most common diseases in almost whole hazelnut producing areas. The disease is caused by two different species, Phyllactinia guttata (Wallr. et Lev.) Fr. and Erysiphe corylacearum U. Braun & S. Takam. For the last 4 years, E. corylacearum, a newly invasive fungus in Turkey, has been caused significant economic losses. In the present study, the efficacy of ammonium, potassium and sodium bicarbonates, and two fungicides were evaluated in field trials against powdery mildew on hazelnuts in Samsun in 2016. The application rates of compounds used in the experiment were as follows: ammonium, potassium and sodium bicarbonates (Sigma-Aldrich, Seelze, Germany) at 1.5, 3, 4.5 and 6% (w/v); Collis® SC (100 g/l Kresoxim methyl +200 g/l Boscalid, BASF, Spain) at 30 ml/100 l and Sulflow® 80 WG (Sulphur 800 g/l, Agrofarm, Turkey) at 400 g/100 l. Of the compounds tested, except for fungicides, sodium was found to be the most effective in controlling the powdery mildew on hazelnuts, followed by potassium and ammonium, respectively. Among those three, ammonium bicarbonate was ineffective against fruit infections of the disease. There was also no significant difference between inhibitory effects of 6% sodium bicarbonate, Collis and Sulflow against the disease (P < 0.05). In addition, bicarbonate salts was phytotoxic to hazelnut leaves at concentrations greater than 1.5%. The results indicate that sodium or potassium bicarbonate solutions seems to be a useful biocompatible fungicide for controlling the powdery mildew on hazelnuts.
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The antibacterial properties of sodium bicarbonate have been known for years, yet the molecular understanding of its mechanism of action is still lacking. Utilizing chemical-chemical combinations, we first explored the effect of bicarbonate on the activity of conventional antibiotics to infer on mechanism. Remarkably, the activity of 8 classes of antibiotics differed in the presence of this ubiquitous buffer. These interactions and a study of mechanism of action revealed that, at physiological concentrations, bicarbonate is a selective dissipater of the pH gradient of the proton motive force across the cytoplasmic membrane of both Gram-negative and Gram-positive bacteria. Further, while components that make up innate immunity have been extensively studied, a link to bicarbonate, the dominant buffer in the extracellular fluid, has never been made. Here, we also explored the effects of bicarbonate on components of innate immunity. Although the immune response and the buffering system have distinct functions in the body, we posit there is interplay between these, as the antimicrobial properties of several components of innate immunity were enhanced by a physiological concentration of bicarbonate. Our findings implicate bicarbonate as an overlooked potentiator of host immunity in the defense against pathogens. Overall, the unique mechanism of action of bicarbonate has far-reaching and predictable effects on the activity of innate immune components and antibiotics. We conclude that bicarbonate has remarkable power as an antibiotic adjuvant and suggest that there is great potential to exploit this activity in the discovery and development of new antibacterial drugs by leveraging testing paradigms that better reflect the physiological concentration of bicarbonate.
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In this study, we investigated the effects of sodium bicarbonate (NaHCO3), potassium bicarbonate (KHCO3), and NaCl, alone or in combination, on raw ground beef. Raw ground beef was mixed with NaHCO3 (5 g/kg; 10 g/kg), KHCO3 (5 g/kg; 10 g/kg), and/or NaCl (5 g/kg), and the results of the treatment(s) were compared with ground beef treated with modified food starch (20 g/kg) or potato starch (20 g/kg). Adding the bicarbonates significantly increased (p < 0.05) pH and water-holding capacity (WHC) of raw ground beef. Bicarbonates with or without salt improved the WHC more than either modified food starch or potato starch. KHCO3 with NaCl provided the best adhesive values in raw ground beef. The bicarbonates and combinations of NaCl maintained the L*- values of the ground beef during retail display storage. Our findings suggest that using bicarbonates increases the WHC by increasing the pH, resulting in raw ground beef that is more tender and adhesive.
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Introdução A avaliação microbiológica em produtos de higiene pessoal constitui uma etapa importante no que se refere à segurança do usuário e à qualidade do produto, visto que a carga microbiana elevada pode acarretar problemas de saúde, especialmente em pessoas imunocomprometidas. Objetivo Verificar o cumprimento das exigências acerca da qualidade microbiológica de cremes e géis dentais adquiridos comercialmente. Material e método Realizou-se a contagem de bactérias e fungos viáveis totais e pesquisa dos patógenos E. coli, Salmonella sp., S. aureus e P. aeruginosa em 21 amostras. Resultado Das amostras analisadas, 52,0% apresentaram crescimento microbiano e 28,6% e 0,21% apresentaram contaminação fúngica e bacteriana, respectivamente, acima dos limites descritos na Farmacopeia Brasileira para preparações de uso tópico (máximo permitido 2 × 10² UFC/g de bactérias e 2 × 10¹ UFC/g de fungos). Nenhuma amostra apresentou os patógenos pesquisados E. coli, Salmonella sp., S. aureus e P. aeruginosa. Conclusão Estes resultados indicam que muitos produtos disponíveis no mercado apresentam qualidade inadequada, demonstrando falhas no controle de qualidade. Para prevenir esta situação, faz-se necessária fiscalização rigorosa e adoção de medidas regulamentadoras e educacionais aliadas ao seguimento das Boas Práticas de Fabricação pelas indústrias fabricantes.
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Unlabelled: Growth of enteropathogenic Escherichia coli E2348/69 was inhibited by bicarbonate in a dose-dependent manner, showing approximately 5% growth reduction at 5 mmol l(-1) while kanamycin at 3·12 μg ml(-1) inhibited growth by 15%, yet when kanamycin and bicarbonate were combined at these concentrations, inhibition increased to 80%. Unexpectedly, at bicarbonate concentrations >20 mmol l(-1) enhancement of the antibiotic activity virtually disappeared, i.e. there was a paradoxical Eagle-like effect. How bicarbonate acts is unclear, but neutral or alkaline pH also enhanced the activity of kanamycin. However, several differences indicated a separate effect of bicarbonate. First, bicarbonate inhibited growth more than the corresponding increments in pH. Second, at low concentration, the antibiotic enhancing effect of bicarbonate was stronger than the effect of pH alone. Third, 5 mmol l(-1) bicarbonate significantly enhanced the activity of kanamycin while the corresponding pH had no effect. Fourth, the Eagle-like effect was exclusive of bicarbonate because changes in pH did not induce an analogous behaviour. Notwithstanding the mechanism, the enhancing effect of bicarbonate was indubitable. Consequently, it seems worthwhile to explore further its potential to improve the efficacy of aminoglycosides and maybe even other antibiotics. Significance and impact of the study: Bicarbonate at a low concentration enhanced the in vitro antibiotic activity of kanamycin and gentamicin. Even though the action mechanism of bicarbonate is hitherto unknown, it seems worthwhile to explore further its capacity to improve the efficacy of aminoglycosides. Clearly, the well-known harmful side-effects of aminoglycosides are a concern. However, it has recently been shown in a fish model that bicarbonate may protect ciliary cells against the damage caused by aminoglycosides. So, it seems possible that bicarbonate could help reduce aminoglycoside dosage at the same time that it might help lessen the damage to auditory ciliary cells in humans.
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Post harvest diseases are a cause of great economical loss to perishables throughout the world. In this review conventional and non-conventional control methods to manage post harvest diseases of the perishables have been discussed in detail in light of relevant work of past.
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The effect of plant resistance inducers, some essential oils and plant extracts on the viability of bio-agents, Bacillus subtilis, Pseudomonas fluorescens and Saccharomyces cerevisiae was evaluated In vitro. Plant resistance inducers, i.e. Potassium mono hydrogen phosphate salt and Calcium chloride, mixture of Humic & Folic acids (AF) were tested. Plant extracts of three plant leaves, i.e. Halfa Bar (Cymbopogon Proximus); Ginger (Zingiber officinale) and Bay laurel (Laurus nobilis) were tested. Commercial essential oils of Cinnamon, Clove and Thyme were also used in the present work. The obtained results revealed that P. fluorescens was highly affected with different tested concentrations of plant resistance inducers followed by B. subtilis and S. serevisiae, respectively. Regarding the inhibitor effect of tested plant extracts, B. subtilis showed the highest sensitivity against tested concentrations of Ginger extract followed by P. fluorescens and S. cerevisiae, respectively. Moreover, another feature was observed with S. cerevisiae that it showed more sensitivity than the other two bacterial isolates against Bay laurel and Ginger extracts concentrations. In vitro tests revealed that the used essential oils had an inhibitory effect against viability of tested bacterial and yeast. The reduction in colony formation of either bacteria or yeast was increased as concentration of tested essential oils was increased to reach its maximum at the highest tested concentration. The obtained results in the present study lead to suggest that the applied dose of such fungicides alternatives should be reviewed when combined with biocontrol agents in integrated control programs. Key words: soil borne pathogenic fungi, viability of antagonistic bacteria and yeast, plant resistance inducers, some essential oils and plant extracts, growth viability.
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The effect of potassium bicarbonate (KHCO3) as an antifungal agent was tested on the fungal growth of Sclerotium cepivorum and Trichoderma strain R39. The growth of the fungal colony, the number and germination of sclerotia formed by S. cepivorum, as well as the antagonism of Trichoderma on the pathogen were evaluated in potato dextrose agar (PDA, Baker®) culture media amended with seven concentrations of KHCO (2, 4, 6, 8, 10, 3 25 and 50 mM). At 50 mM, the growth of S. cepivorum was inhibited 34.5%, whilst for Trichoderma inhibition was 83.1%. At the concentrations of 10, 25 and 50 mM of KHCO3 sclerotia formation by S. cepivorum was significantly inhibited (51.5%, 77.0% and 100%, respectively), likewise the sclerotia germination (18%, 78% and 86%, respectively). When both fungi were confronted in a KHCO3 –enriched PDA, this chemical compound did not affect the antagonistic capability of Trichoderma towards the pathogen. After 144 h, Trichoderma showed an invasion of 70% over the colony of S. cepivorum, at 50 mM. The potential benefits of KHCO to inhibit both growth and development of S. cepivorum were 3 evident, since it reduced either fungal growth or both formation and germination of sclerotia.
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In vitro experiments showed that sodium bicarbonate (SBC) was effective in inhibiting the growth of Mycogone perniciosa. The inhibition of radial growth, germination and germ tube elongation of chlarnydospores was 100.0%, 73.9%, 79.1 %, respectively, at 4% SBC. Complete inhibition of the germination and germ tube elongation of conidia was achieved by 4% SBC. Seven experiments were conducted to test the hi vivo efficacy of sodium bicarbouate and reduced dose of prochloraz manganese either alone or in combination. Treatments were applied to casing soil twice by drenching 2 h before casing and 2 days after casing. In seven in vivo experiments, the effect of SBC in inhibiting M. perniciosa wag inconsistent. The efficacy of the combination of SBC with reduced dose (10% of label dose) of prochloraz mangenese were not significantly and consistently different from that of the label dose of prochloraz manganese in inhibiting the disease and increasing the yield in three repeated experiments. Similarly, in the bags treated with the combination of sodium bicarbonate and reduced dose of prochloraz manganese, the amount of sclerodermoid masses were reduced to 309 g from 1048 g in the control. Sodium bicarbonate treatment neither impaired quality of sporophores nor reduced the yield.
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In vitro experiments showed that ammonium bicarbonate and aqueous extracts of oregano were effective in inhibiting conidia germination and germ-tube elongation of Venturia inaequalis. Complete inhibition was achieved by 1% ammonium bicarbonate, 2% oregano extract and 0.01% synthetic fungicide difenoconazole. Two orchard experiments were conducted on the highly susceptible cv. Mutsu to apple scab to investigate the efficacy of ammonium bicarbonate alone or in combination with an aqueous extract of oregano for the control of apple scab. In 2008 and 2009, except for the applications of 1% aqueous extract of oregano, the applications of ammonium bicarbonate (0.5 and 1%) and difenoconazole (0.01%) to trees at 10-day intervals significantly reduced disease incidence and severity on leaves and fruit compared to the water-treated control. In both years, the efficacy of 0.5 and 1% ammonium bicarbonate in inhibiting both disease incidence and severity on leaves and fruit was equally effective in all monthly assessments from June to September. Combining 0.5 and 1% ammonium bicarbonate with 1% aqueous extract of oregano did not significantly improve the efficacy of stand-alone applications of treatments in the final assessment in 2008 and 2009. All treatments were neither phytotoxic to leaves and fruit nor did they adversely affect quality parameters of fruit including physiological disorders and taste both at harvest and after storage. These results indicate that ammonium bicarbonate treatment may be applied as an alternative chemical for the control of apple scab.
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The potential of using Pantoea agglomerans (strain CPA-2) alone, or in combination with sodium bicarbonate or sodium carbonate solutions, for control of Penicillium digitatum (green mold) and Penicillium italicum (blue mold) on oranges was investigated under ambient (20 °C) and cold storage (3 °C) conditions. P. agglomerans controlled both pathogens on oranges at 2 × 108 cfu ml-1. The biocontrol agent was found to be completely tolerant to 2% sodium bicarbonate at room temperature, although its culturability was reduced by > 1000-fold after 30 min in 2% sodium carbonate. The efficacy of P. agglomerans for control of green mold was improved when combined with sodium bicarbonate, resulting in complete and 97.6% reduction of decay incidence at 3 °C and 20 °C, when compared to untreated controls. Satisfactory results were also obtained with the combined treatment for control of blue mold. P. agglomerans grew well inside wounds on oranges at both 20 °C and 3 °C. In contrast, it showed a reduced growth on the surface of intact fruit. Sodium bicarbonate at 2% concentration did not noticeably affect antagonist population development. Thus, use of bicarbonate treatment at 2% followed by the antagonist P. agglomerans CPA-2 could be an alternative to chemicals for control of postharvest diseases on oranges.
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The effects of sodium bicarbonate (NaHCO3) on pathogenicity of Colletotrichum musae and its potential to control postharvest diseases of bananas were determined. Addition of NaHCO3 reduced mycelial growth, spore production, spore germination and appressoria production of C. musae, in vitro by increasing pH (from 6.9 to 8.7) of the culture medium (PD broth). The pH of 8.59, created by 100 mM NaHCO3 completely inhibited spore production. Postharvest dip treatment in 300 mM NaHCO3 for 10 min reduced the lesion area of anthracnose on artificially inoculated banana fruit. Natural infections of anthracnose, crown rot and blossom end rot were also reduced significantly in fruit that were treated with 300 mM NaHCO3 for 10 min. Efficiency of integrating NaHCO3 with a bacterial antagonist, Burkholderia spinosa for controlling postharvest diseases of bananas was also determined. Dipping banana fruit in 300 mM NaHCO3 solution for 10 min followed by dipping in B. spinosa suspension in nutrient broth (cell concentration 1 × 108 cfu/mL) effectively controlled anthracnose, crown rot and blossom end rot of bananas (var. Kolikuttu). Dipping bananas in 300 mM NaHCO3 increased pH, total soluble solids and thickness of the fruit peel which may have an indirect or cumulative effect on the reduction of postharvest disease development in bananas.
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The potential of using the biocontrol agent Candida oleophila and sodium bicarbonate solution alone or in combination to reduce anthracnose caused by Colletotrichum gloeosporioides on papaya (Carica papaya L.) in storage was investigated. Treatment with 2% sodium bicarbonate did not significantly affect the growth of the biocontrol agent The efficacy of sodium bicarbonate at 2% for control of anthracnose increased when combined with C. oleophila strain (1–182) resulting in significant reduction of disease incidence at 13.5°C and 95% RH for 14 days and afterwards by 2 days at simulated marketing conditions (25°C, 75%). The growth of C. gloeosporioides was reduced significantly in the presence of C. oleophila in both inoculated and naturally infected fruits. Thus, use of sodium bicarbonate at 2% with the antagonist C. oleophila is a promising alternative to chemicals to control anthracnose, a major postharvest disease on papaya during storage.
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The control of postharvest gray mold on detached table grape berries by treatment with carbonate and bicarbonate salt solutions, alone or with chlorine, ozone, or ethanol, was evaluated. Sodium carbonate (SC), potassium carbonate (PC), sodium bicarbonate (SBC), potassium bicarbonate (PBC), and ammonium bicar- bonate (ABC) were tested without control of pH for their toxicity to spores of Botrytis cinerea in vitro, and the concentrations that stopped germination of 95% (EC95) of the spores were 16, 17, 36, 58, and 163 mM, respectively. When bicarbonate solutions were adjusted to pH 7.2 (±0.2), the mean EC95 concentrations for two B. cinerea strains of ABC, SBC, and PBC were 48, 102, and 112 mM, respectively. In 1.5 µg/ml of ozone in water, 50% and 95% mortality of spores of B. cinerea occurred after 21.3 and 35.6 sec, respectively. In tests to control gray mold on grapes, among the bicarbonates, each applied at 500 mM, ABC was significantly more effective than SBC and PBC. It was also superior to PC (100 mM) and chlorine (200 µg/ml) and equal in effectiveness to SC (100 mM) and ethanol (70% wt/vol). The addition of 200 µg/ml chlorine to the bicarbonate salts significantly decreased gray mold incidence. Ozone in water at 10 µg/ml significantly controlled gray mold, although its efficacy was irregular and dependent on grape condition. Among all the treatments, berry condition was an important factor; for example, there was significant decrease in control when wounded berries were treated compared to unwounded berries. The quality of grapes after treatment with ABC, SBC, ethanol, and chlorine was acceptable; ozone in water caused minor rachis injury; while severe injuries, mostly brown spots on berries, occurred after SC, PC, and PBC treatments.
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The objective of this study was to investigate alkaline treatments of cattle manure to kill coliforms, Escherichia coli O157:H7 and Salmonella Typhimurium DT104 based on their inhibition by carbonate ion and ammonia. Pure cultures of S. Typhimurium DT104 and E. coli O157:H7 strains were treated with sodium carbonate and ammonia to determine threshold inhibitory concentrations. Fresh cattle manure samples were inoculated with the same strains and their survival was determined after addition of sodium hydroxide, ammonium sulphate, sodium carbonate and/or urea. Control of CO and NH3 concentrations in manure by pH adjustment to 9.5 with sodium hydroxide to more than 5 and 30 mmol l-1, respectively, killed more than 106 cells g-1 in 7 days. Addition of sodium carbonate enhanced the killing effect of NaOH by increasing the CO and NH3 concentrations. Addition of 100 mmol l-1 urea, produced high levels of CO and NH3 and decreased all bacterial counts by at least 106 cells g-1 after 7 days. Reduction of food-borne pathogens in manure can be achieved by a combination of high concentrations of CO and NH3 which are pH-dependent parameters. Addition of urea could provide a simple manure treatment by combining both antimicrobial factors.
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Carbon dioxide is effective for extending the shelf-life of perishable foods by retarding bacterial growth. The overall effect of carbon dioxide is to increase both the lag phase and the generation time of spoilage microorganisms; however, the specific mechanism for the bacteriostatic effect is not known. Displacement of oxygen and intracellular acidification were possible mechanisms that were proposed, then discounted, by early researchers. Rapid cellular penetration and alteration of cell permeability characteristics have also been reported, but their relation to the overall mechanism is not clear. Several researchers have proposed that carbon dioxide may first be solubilized into the liquid phase of the treated tissue to form carbonic acid (H2CO3), and investigations by the authors tend to confirm this step, as well as to indicate the possible direct use of carbonic acid for retarding bacterial spoilage. Most recently, a metabolic mechanism has been studied by a number of researchers whereby carbon dio...
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The effect of substituting sodium bicarbonate for sodium chloride in frankfurters was evaluated using chemical and sensory criteria. Frankfurters were formulated and prepared using one of three treatments: (a) 2% sodium chloride control, (b) 1% sodium bicarbonate and 1% sodium chloride or (c) 2% sodium bicarbonate. Substitution of sodium bicarbonate raised the pH from 6.0 to 7.5 and 8.2 (treatments a, b and c, respectively). Percent free water decreased with sodium bicarbonate substitution from 41.3 to 31.7 and 21.6. Sodium bicarbonate substitution did not significantly affect Warner-Bratzler shear force values or sensory determination of moistness or tenderness. However, sensory evaluations of texture and mouthfeel and off-flavor intensity were less desirable with increased sodium bicarbonate content. Visual evaluations indicated that substitution of sodium bicarbonate for sodium chloride resulted in frankfurters having a darker brown color. Scanning electron microscopic evaluation of frankfurters did not show evidence of major structural differences. Frankfurters in vacuum-packaged bags were stored for up to 30 d in a 4°C lighted retail case. Total plate counts were not significantly different between treatments on days 0, 15 or 30 of storage. These results indicate a potential use of sodium bicarbonate to alter pH and percent free water of emulsified meat products; however, some sensory properties are diminished when sodium chloride is replaced with sodium bicarbonate.
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ABSTRACTA study was designed to evaluate the use of low levels of sodium (0.25, 0.5, 1%) and potassium (0.25, 0.5%) bicarbonate on the sensory, microbial and functional properties of frankfurters. Both sodium and potassium bicarbonate resulted in higher pH values than control (no bicarbonate) on day 0 but differences diminished after storage at 4°C for 22 days. At the 0.5% level of addition, both sodium and potassium bicarbonate treatments had lower percent free water when compared to controls. The addition of high levels of bicarbonate resulted in diminished sensory properties; however, low levels had sensory characteristics in the acceptable range. No differences were detected between treatments for aerobic plate counts, anaerobic plate counts or yeast and mold counts. Results indicate an acceptable product can be produced using low levels of either sodium or potassium bicarbonate. The use of low levels of bicarbonate also results in beneficial changes of some physical properties.
Article
A soyflour was prepared by soaking the beans in 9 volumes of 0.5% NaHCO3 overnight (pH 8.5), steamed at 100°C for 30 min, dried at 50–60°C under vacuum, then ground to flour. The flour had a light tan color and no objectional beany odor. The composition of the flour was 48% protein, 19% flour, 5% ash, and 3.5% moisture. No lipoxygenase nor antitrypsin activity was detected in the flour. The phytate content was 0.75%. Protein solubility, emulsifying capacity, foaming capacity, oil and water absorption of the flour was determined. The results showed that the flour prepared from biocarbonate soaked and steamed soybeans possessed desirable functional characteristics except protein solubility was decreased. Two products, noodles and bread, were prepared by using the soyflour as an ingredient. Sensory evaluation of the products revealed that both products were well accepted. This study was supported in part by the George Washington Carver Agricultural Experiment Station, (USDA/CSRS Grant No. Al X-3JYL-05). The authors acknowledge the assistance of Mr. Leo G. Holmes, U.S. Army Natick Research and Development Command, Natick, Mass., in conducting amino acid analysis of soyflour.
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Inhibition of yeast function by ethanol and by high substrate concentrations is well recognized and, to a limited extent, quantified. The role of carbon dioxide in affecting yeast metabolism (particularly growth processes) is not clear although inhibition is generally found at moderate to high concentrations of the dissolved gas. A similar situation exists with other microorganisms and with other fermentation systems. An understanding of the role of carbon dioxide, and particularly of its inhibitory effects on enzyme action and membrane function, is required if the observed global inhibition of yeasts and other fermentation systems is to be partitioned to its appropriate causes.
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The potential of sodium bicarbonate to inhibit growth of and aflatoxin synthesis by Aspergillus parasiticus was examined in Czapek's agar (CA), a medium in which fluorescence under UV light indicates aflatoxin production. Incorporation of sodium bicarbonate (SB) into CA at 0.011, 0.022, and 0.033 mol% reduced cell viability 63-, 10(3)-, and greater than 10(7)-fold, respectively. Colonies resulting from surviving cells did not fluoresce under UV light, but thin-layer chromatography analysis of culture extracts detected aflatoxins. Potassium bicarbonate (KB) at 0.011 and 0.022 mol% produced inhibitory effects similar to those of SB, but NaCl and silica had no effect. After 7 days, control cultures had the normal aflatoxin distribution (B1 greater than G1 greater than B2 greater than G2), but this distribution shifted to B2 greater than B1 approximately equal to G2 greater than G1 during prolonged incubation. Cultures supplemented with SB and KB contained mostly aflatoxins B1 and G1 after 28 days. Both SB and KB raised the pH of CA to 7.5 to 8.5 at the time of growth. Culture growth on CA adjusted to pH 7.5 to 8.5 with NaOH was not inhibited but exhibited reduced fluorescence and elevated levels of aflatoxins B1 and G1. Thus, while bicarbonate inhibition of growth could not be attributed to pH elevation, the lack of culture fluorescence on CA-SB and CA-KB and the altered aflatoxin distribution were caused by the ability of SB and KB to elevate pH.
Article
The topical application of hydrogen peroxide (H2O2) and sodium bicarbonate (NaHCO3), individually and in combination, has been used empirically in the treatment of periodontal diseases. In this study, we examined both minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of these disinfectants individually and in combination against selected facultative, Gram-negative oral bacteria in a microtiter dilution assay. The bacteria studied included Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, Eikenella corrodens, and Capnocytophaga gingivalis. These bacteria exhibited MBC (one hr) values ranging from 75 mumol/L to greater than 10 mmol/L and MIC from less than 5 to 500 mumol/L for H2O2. The tested bacteria exhibited MIC values for NaHCO3 of from 23 to 182 mmol/L, and the MBC (one hr) exceeded 728 mmol/L for most of the strains examined. At sublethal (sub-MIC) concentrations, sodium bicarbonate antagonized the ability of H2O2 to inhibit bacterial growth in MIC assays, but sublethal concentrations of H2O2 had no effect on the MIC values of NaHCO3. Lethal concentrations of H2O2 and NaHCO3 exhibited synergistic antimicrobial activity in combination in one-hour bactericidal assays. Since the bactericidal properties of these antimicrobial agents are synergistic, we conclude that it may be rational to use them in combination to treat certain forms of periodontal disease. Also, lower and perhaps safer concentrations of H2O2 can be used in combination with NaHCO3 when oxidative antimicrobial chemotherapy is indicated.
Article
Morphological changes of S. mutans NCTC 10449S associated with growth in modified Jordan medium and FMC medium (Terleckyj et al., Infect. Immun. 11:649-655, 1975) were studied by scanning electron microscopy. The cells were bacillary in Jordan medium, but coccoid and of unequal size in FMC. Transfer of the cells from Jordan medium to FMC and vice versa reversed their shapes, as did salt exchange between these media. Morphological changes could not be ascribed to either medium pH, concentration of P, or Na+/K+ ratio. However, they were growth dependent, since the changes did not occur when the cells were suspended in salt components alone or in media supplemented with protein synthesis inhibitors. Only a high bicarbonate/K+ ratio, as in FMC, produced spherical cells, whereas cells remained bacillary in medium with a low bicarbonate/K+ ratio, as in Jordan medium. Manipulating this ratio in other media resulted in similar shape changes. Thus, the shape of S. mutans 10449S can be dictated by the ratio of bicarbonate to K+ in the growth medium.
Article
Organisms representative of soil, skin and fecal flora and of supragingival and subgingival flora were tested for inhibition of growth and killing by various salts (NaHCO3, NaCl, MgSO4). The antimicrobial activities of KHCO3, NaF, sodium lauryl sulfate (SLS) and chloramine T were also compared with that of NaHCO3, and the rate at which NaHCO3 exerts its bactericidal effect was studied. Suspected periodontal pathogens were more susceptible to salts than were control non-oral bacteria. Supragingival plaque organisms showed intermediate susceptibility. Periodontal pathogens were more susceptible to NaHCO3 than to NaCl; NaHCO3 and KHCO3 showed similar activity against all strains tested. Accordingly, the antibacterial activity of NaHCO3 is not simply an osmotic effect and is due to the bicarbonate ion. NaF, SLS and chloramine T had greater antimicrobial activity than NaHCO3. Supragingival bacteria required at least 6-hour exposure to 1.0 M NaHCO3 to produce 99% lethality (decrease colony-forming units by 2 log10), whereas selected periodontal pathogens were killed more rapidly (30-120 minutes). The higher the concentration of bicarbonate, the faster the lethality. Morphologic examination by transmission electron microscopy of organisms exposed to bactericidal salt concentrations revealed marked fibrillar condensations within the cytoplasm and shrinkage of the cytoplasm from the outer membrane. For NaHCO3 to be clinically effective, a high concentration must be introduced into the periodontal pocket and maintained there long enough to kill periodontal pathogens. Furthermore, NaHCO3 must be reapplied often enough to prevent recolonization by these pathogens. An advantage of NaHCO3 over NaF, SLS and other antimicrobial agents is its safety, availability and low cost.
Article
This study investigated the effects of sodium bicarbonate and hydrogen peroxide on the microbial flora of 4 to 7 mm periodontal pockets. Four selected patients were instructed to brush assigned quadrants daily with a sodium bicarbonate-3% hydrogen peroxide paste utilizing a split-mouth design. The paste was pumped between the teeth and gingiva via sulcular brushing and a Perio Aid. The control sides were treated in the identical manner with fluoridated paste. Probing depths on each patient were taken on Days 1 and 21 and examined under dark-field microscopy. For each sample, morphology and motility of all cells were recorded. The data were analyzed by three factor repeated measures analysis of variance. No statistically significant differences were found between the control and medicament sites at the 0.005 level regarding changes in the microbial flora. Probing depths were reduced during the study. However, similar results were found on both medicament and control sites. It appeared that sodium bicarbonate and hydrogen peroxide have no unusual benefits in reducing the microbial flora of periodontal pockets.
Article
A model is presented suggesting the interaction of CO(2) and bicarbonate on lipids of the cell membrane. The interfacial tensions between water and oil (benzene) phases were measured using the stalagmometer and the sessile drop methods. Effects of electrolyte solutions and of CO(2) on molecular arrangement at the interface were calculated. Chloride solutions against oleic acid in benzene produced little decrease in interfacial tension from that measured for pure water against the oil phase. Presence or absence of CO(2) caused no change in interfacial tension of water or chloride solutions against the oil phase. Bicarbonate salts in the absence of CO(2) caused marked decreases in interfacial tension from that measured for water or chloride solutions. Concomitant with this decrease in interfacial tension were an increase in hydration of the interface and changes in molecular spacings of the lipid. This hydration may be considered as reflecting a more ionic-permeable cell membrane. The addition of CO(2) to the bicarbonates caused an increase in interfacial tension of the model, approaching that of the chlorides, with decreased hydration of the interface. Viewed as occurring at the cell membrane this would make the lipid more continuous and decrease the ease of ionic penetration. In this way the action of bicarbonates and CO(2) at the interface suggests an explanation of the action of CO(2) on the cell.
A review of ef-fects of carbon dioxide on microbial growth and food quality. J. Food Protc ?ct. 48: 532. Harmc ~n, S.M. 1984. Clostridium perfrin ens: enumeration and identifi-n. Chl 17
  • P A Daniels
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Daniels, P.A., Krishnamurthi, R., and Rizvi, S.S.H. 1985. A review of ef-fects of carbon dioxide on microbial growth and food quality. J. Food Protc ?ct. 48: 532. Harmc ~n, S.M. 1984. Clostridium perfrin ens: enumeration and identifi-n. Chl 17. In " Bacteriological An f. ytmal Manual, " p. 17.00-17.10. AOAC, Arlin Jones, R.P. an tit on, VA.
Antimicrobial activity of sodium bicarbonate against food-relate bacteria and yeasts
  • L G Corral
Corral, L.G. 1987. Antimicrobial activity of sodium bicarbonate against food-relate bacteria and yeasts. M.S. thesis, Rutgers Univ., New Brims-wick, NJ.
Biophysical factors in growth Manual of Methods for General Bacteriology
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Costilow, R.N. 1981. Biophysical factors in growth. In " Manual of Methods for General Bacteriology, " p. 66. American Society for Microbiology, Washin n,DC.
Characterization of a flour from sodium bicarbonate soaked and steamed sovbeans
  • J Y Lu
  • Al Jassen
Lu, J.Y. and Al Jassen, MS. 1986. Characterization of a flour from sodium bicarbonate soaked and steamed sovbeans. J. Foo B