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The time course of the biomass concentration X (g DW /l) and the MEK residual concentration (ppm) for the A5.7 strain.
Source publication
Volatile organic compounds are considered as major sources of air pollution. They cause toxicity problems, bad odors, global warming, etc. Methyl ethyl ketone (MEK) is used in the formulation of lacquer type paints, varnishes, cleaners, thinners, etc. and in many other industries such as the manufacture of synthetic leather and in the decaffeinatio...
Contexts in source publication
Context 1
... results of the time course of the biomass con- centration X and the residual MEK concentration for the A5.7 strain are presented graphically in Fig. 4. The profiles of the time course of the experimental specific consumption rate of MEK (r x,MEK ) are shown in Fig. ...
Context 2
... profiles of the specific growth rates vs. the residual MEK concentration are shown in Fig. 6. The growth of A5.7 strain varied regularly. Its specific growth rate quickly reached a maximum and then diminished gradually with the concomitant substrate concentration decrease (Fig. 4). The results show that ...
Context 3
... there is a decrease in the MEK consumption rate over time (Fig. 5). Strain A5.7 seemed to be efficient in terms of MEK utilization. Indeed, the complete substrate degradation occurred after only 72 h of incubation (Fig. 4). Growth evolved smoothly with MEK consumption and was characterized by the highest maximum growth rate of 0.132 h −1 in comparison with the rest of the isolates (Table 1). The strain A5.7 was therefore selected among the set of the isolated ...
Citations
... Mineral salt medium (MSM) (Table S1) agar plates were supplemented with metribuzin at concentrations ranging from 1 to 200 mg/L, and the isolates were surface-inoculated and incubated at 30 • C for one week. Positive growth indicated the capacity to degrade metribuzin, and the isolates that grew at the highest herbicide concentration were selected for further testing in a liquid MSM medium containing 50 mg/L metribuzin [34,35]. The selected actinobacterial isolates were characterized according to standard protocols. ...
Citation: Rebai, H.; Sholkamy, E.N.; Abdelhamid, M.A.A.; Prakasam Thanka, P.; Aly Hassan, A.; Pack, S.P.; Ki, M.-R.; Boudemagh, A. Soil Actinobacteria Exhibit Metabolic Capabilities for Degrading the Toxic and Persistent Herbicide Metribuzin. Toxics 2024, 12, 709. https://doi. Abstract: Metribuzin, a widely used triazine herbicide, persists in agricultural soils and poses significant environmental pollution threats globally. The aim of this study was to investigate the biodegradation of metribuzin by actinobacterial strains in vitro at different environmental conditions. From an initial screen of 12 actinobacterial strains, four bacteria exhibited robust growth in the presence of the metribuzin as the sole carbon source at 50 mg/L concentration. The optimization of metribuzin biodegradation under different conditions (pH, temperature and inoculum size) using a spectrophotometric method revealed that maximum degradation of metribuzin occurred at a pH of 7.2, a temperature 30 • C, and at an inoculum volume of 4%. Subsequent GC-MS validation confirmed the remarkable biodegradation capabilities of the actinobacterial isolates, where the strain C1 showed the highest rate of metribuzin degradation of 83.12%. Detailed phylogenetic identified the active strains as Streptomyces toxytricini (CH), Streptomyces stelliscabiei (B2), and two Streptomyces heliomycini (C1, C3). Structural analysis by ATR-FTIR spectroscopy confirmed the extensive biotransformation of the herbicide molecule. Our findings highlight the immense untapped potential of soil actinobacteria, particularly the Streptomyces heliomycini C1 strain, as versatile bioremediation agents for removing persistent agrochemical pollutants.
... Mineral salt medium (MSM) (Table S1) agar plates were supplemented with metribuzin at concentrations ranging from 1 to 200 mg/L, and the isolates were surface-inoculated and incubated at 30 • C for one week. Positive growth indicated the capacity to degrade metribuzin, and the isolates that grew at the highest herbicide concentration were selected for further testing in a liquid MSM medium containing 50 mg/L metribuzin [34,35]. The selected actinobacterial isolates were characterized according to standard protocols. ...
Citation: Rebai, H.; Sholkamy, E.N.; Abdelhamid, M.A.A.; Prakasam Thanka, P.; Aly Hassan, A.; Pack, S.P.; Ki, M.-R.; Boudemagh, A. Soil Actinobacteria Exhibit Metabolic Capabilities for Degrading the Toxic and Persistent Herbicide Metribuzin. Toxics 2024, 12, 709. https://doi. Abstract: Metribuzin, a widely used triazine herbicide, persists in agricultural soils and poses significant environmental pollution threats globally. The aim of this study was to investigate the biodegradation of metribuzin by actinobacterial strains in vitro at different environmental conditions. From an initial screen of 12 actinobacterial strains, four bacteria exhibited robust growth in the presence of the metribuzin as the sole carbon source at 50 mg/L concentration. The optimization of metribuzin biodegradation under different conditions (pH, temperature and inoculum size) using a spectrophotometric method revealed that maximum degradation of metribuzin occurred at a pH of 7.2, a temperature 30 • C, and at an inoculum volume of 4%. Subsequent GC-MS validation confirmed the remarkable biodegradation capabilities of the actinobacterial isolates, where the strain C1 showed the highest rate of metribuzin degradation of 83.12%. Detailed phylogenetic identified the active strains as Streptomyces toxytricini (CH), Streptomyces stelliscabiei (B2), and two Streptomyces heliomycini (C1, C3). Structural analysis by ATR-FTIR spectroscopy confirmed the extensive biotransformation of the herbicide molecule. Our findings highlight the immense untapped potential of soil actinobacteria, particularly the Streptomyces heliomycini C1 strain, as versatile bioremediation agents for removing persistent agrochemical pollutants.
... Selective media used for the isolation of Actinobacteria were: AF (Kitouni 2007), Czapek-dox modified (Soler et al. 2018), ISP4 (the International Streptomyces Project No. 4) (Silini et al. 2016) and Olson (Bensultana et al. 2010). The antibiotic nalidixic acid (20 μg/ml) and the antifungal cycloheximide (50 μg/ml) were added to the isolation media (Goodfellow et al. 1996). ...
... They recovered five Streptomyces strains able to degrade the commercial fungicide ortiva in a total of seven isolated. Silini et al. (2016) at Oued El Athmania WWTP were only able to isolate strains from the genus Streptomyces. On the other hand, the isolation of Micrococcus in sewage treatment plants is widely reported. ...
The pollution of water resources by pesticides poses serious problems for public health and the environment. In this study, Actinobacteria strains were isolated from three wastewater treatment plants (WWTPs) and were screened for their ability to degrade 17 pesticide compounds. Preliminary screening of 13 of the isolates of Actinobacteria allowed the selection of 12 strains with potential for the degradation of nine different pesticides as sole carbon source, including aliette, for which there are no previous reports of biodegradation. Evaluation of the bacterial growth and degradation kinetics of the pesticides 2,4-dichlorophenol (2,4-DCP) and thiamethoxam (tiam) by selected Actinobacteria strains was performed in liquid media. Strains Streptomyces sp. ML and Streptomyces sp. OV were able to degrade 45% of 2,4-DCP (50 mg/l) as the sole carbon source in 30 days and 84% of thiamethoxam (35 mg/l) in the presence of 10 mM of glucose in 18 days. The biodegradation of thiamethoxam by Actinobacteria strains was reported for the first time in this study. These strains are promising for use in bioremediation of ecosystems polluted by this type of pesticides.
... Recent years, the biological, microbial and natural mediated waste water treatment is highly recommended due to the more advantages including high sugar, polysaccharides and poly-β-hydroxybutyric acid (Bensultana et al., 2010). It has various growth substrates with high molecular weight that increased in the substances of sugars, polysaccharides, proteins, aromatic hydrocarbon, and their compounds (Silini et al., 2015). Among the bacterial community, actinomycetes is concentrated more in waste water treatment based on the excellent production of treatment like substances. ...
Recent years, heavy metal reduction of contaminated atmosphere using microbes is heightened worldwide. In this context, the current study was focused on heavy metal resistant actinomycete strains were screened from effluent mixed contaminated soil samples. Based on the phenotypic and molecular identification, the high metal resistant actinomycete strain was named as Nocardiopsis dassonvillei (MH900216). The highest bioflocculent and exopolysaccharide productions of Nocardiopsis dassonvillei (MH900216) was confirmed by various invitro experiments result. The heavy metal degrading substances was characterized and effectively confirmed by Fourier transform infrared spectroscopy (FT-IR), X-Ray Diffraction (XRD), Scanning electron microscope (SEM). Further, the heavy metal sorption ability of actinomycete substances bioflocculent was exhibited 85.20%, 89.40%, 75.60%, and 51.40% against Cd, Cr, Pb and Hg respectively. Altogether, the bioflocculent produced actinomycete Nocardiopsis dassonvillei (MH900216) as an excellent biological source for heavy metal reduction in waste water, and it is an alternative method for effective removal of heavy metals towards sustainable environmental management.
... This affects a great biodiversity, rich and diversified in actinobacteria, to which corresponds a wide chemodiversity of metabolites. A number of actinobacteria has been isolated from different ecosystems including Saharan plants [34,38,39], caves [40], waste water [41,42], river sediments [43], hypersaline areas [44][45][46][47][48][49][50][51], Saharan desert soil [22,52], and derived algae [53]. The most studied sampling sites for the isolation of actinobacteria are listed in Figure 1. ...
... Khebizi et al. [104] reported significant antifungal activity observed for 38 and 39 (with MIC values estimated between 2 and 75 µg/mL against representatives of the Aspergillus, Fusarium and Penicillium genera as well as C. albicans), but their known high toxicity to eukaryotic cells prevents any clinical applications. A series of polyether antibiotics including nigericin (40), epinigericin (41), abierixin (42), and the new grisorixin methyl ester (43) were isolated from the Streptomyces youssoufiensis SF10 strain collected from Chélia Mountain, in Khenchela (North-eastern Algeria) [105]. The online coupled HPLC-ESIMS analysis provided the full polyether profile, and the preparative HPLC technique in the reversed phase condition gave pure compounds, which were identified by extensive NMR and ESI-MS spectra in comparison with reported data. ...
Actinobacteria, in particular “rare actinobacteria” isolated from extreme ecosystems, remain the most inexhaustible source of novel antimicrobials, offering a chance to discover new bioactive metabolites. This is the first overview on actinobacteria isolated in Algeria since 2002 to date with the aim to present their potential in producing bioactive secondary metabolites. Twenty-nine new species and one novel genus have been isolated, mainly from the Saharan soil and palm groves, where 37.93% of the most abundant genera belong to Saccharothrix and Actinopolyspora. Several of these strains were found to produce antibiotics and antifungal metabolites, including 17 new molecules among the 50 structures reported, and some of these antibacterial metabolites have shown interesting antitumor activities. A series of approaches used to enhance the production of bioactive compounds is also presented as the manipulation of culture media by both classical methods and modeling designs through statistical strategies and the associations with diverse organisms and strains. Focusing on the Algerian natural sources of antimicrobial metabolites, this work is a representative example of the potential of a closely combined study on biology and chemistry of natural products.
... To our knowledge, in Algeria, only the study by Silini et al. [55] was conducted on the isolation of actinobacteria from activated sludge from the El Athmania wastewater treatment plant in the Mila region. ...
Background
The emerging antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are a pressing global concern. Furthermore, the limited number of available antifungal agents requires the discovery of new antimicrobials.
Introduction
This paper focused on the isolation and characterization of an actinobacterium designated S10, the study of its antimicrobial activity, on the one hand, and the optimization of antifungal production using statistical methods, on the other hand.
Methods and Results
A haloalkaliphilic actinobacterium designated S10 was isolated from a wastewater treatment plant in the Souk-El-Tenine region (Bejaia, Algeria). This strain showed a broad spectrum of activity against bacteria (B. subtilis, L. innocua, M. luteus, S. aureus, MRSA, E. coli, P. aeruginosa, S. Typhi, and V. cholerae), molds (A. niger, G. geotricum, and F. oxysporum) and a pathogenic yeast (C. albicans). The extracellular enzymes producer Nocardiopsis sp. S10 was identified based on morphological, chemical, and 16S rRNA gene sequencing analysis. The best antimicrobial production was achieved on Mincer-Sea-Water (MSW) solid medium, and the antibiotics produced were extracted with ethyl acetate. For antifungal production, central composite design (CCD) and response surface methodology (RSM) were used to optimize the culture medium formulation.
Conclusion
Optimal antifungal activity was achieved using a mixture of 2 g. L-1 starch, 2 g. L-1 of yeast extract and 2.75 g. L-1 of peptone at pH = 9.2. The application of the statistical approach stimulated a good yield of anti-C. albicans activity, corresponding to an increase of 72.22% compared to the non-optimized conditions.
From an agricultural soil sample from the region of Ain M'Lila and a sample of activated sludge from the Ibn Ziad-Constantine wastewater treatment plant, we isolated respectively 80 and 18 phenotypically different actinobacteria. The samples in question were the subject of a physic-chemical analysis. Firstly, we conducted a functional study by testing these isolates on a minimum solid medium supplemented with 500 mg/L of different pesticides most commonly used in Algeria, namely the Ortiva and Rodazime fungicides. Insecticides like Karate, Phoenix, Dursban and Cypermethrin. Herbicides in several commercial forms such as Mamba, Zoom, Glyphosate, Herbasate, Roundup,
Traxos and Axial to characterize their abilities to use these pesticides as the sole source of carbon and energy. The results showed that the majority of isolates had the ability to degrade these synthetic compounds. Thus, in this thesis work, we have been interested in testing the ability of these isolates to degrade BTEX, which is an important family of volatile organic compounds. They contaminate various ecosystems such as air, surface water, groundwater and soil. These compounds have very toxic effects on humans and animals. Several microorganisms have been tested for their ability to degrade
BTEX. Others have unfortunately been neglected despite their interesting metabolic and physiological aptitudes. In the present study, we tested the degradation of these compounds by isolated actinomycetes taken individually or in consortia. The results of growth and degradation kinetics showed that 20 actinobacteria and 2 reconstituted consortia were able to use at least one BTEX compound as the sole source of carbon and energy. Of these, four from activated sludge and one from agricultural soils degraded all these volatile organic compounds in vitro under aerobic conditions at concentrations ranging from 1400 to 1500 mg/L in 72 to 96 h of incubation. The second part of this
work aimed to identify active isolates. The physiological study informed us about the remarkablemetabolic diversity of the isolates tested. In addition, a taxonomic study was
conducted by sequencing16S rRNA of 25 strains. This identification showed that twenty-one of these isolates belonged to the genus Streptomyces and three to the genus Nocardia. This result is very encouraging and shows that actinomycetes that come from sewage treatment plants and agricultural soils have the ability to biodegrade these organic volatil compounds and pesticides. The isolated strains are excellent candidates for bioremedion of terrestrial and aquatic sites polluted by these xenobiotics.
Bioaerosols are defined as airborne particles (0.05–100 μn in size) of biological origin. They are considered potentially harmful to human health as they can contain pathogens such as bacteria, fungi, and viruses. This review summarizes the most recent research on the health risks of bioaerosols emitted from wastewater treatment plants (WWTPs) in order to improve the control of such bioaerosols. The concentration and size distribution of WWTP bioaerosols; their major emission sources, composition, and health risks; and considerations for future research are discussed. The major themes and findings in the literature are as follows: the major emission sources of WWTP bioaerosols include screen rooms, sludge-dewatering rooms, and aeration tanks; the bioaerosol concentrations in screen and sludge-dewatering rooms are higher than those outdoors. WWTP bioaerosols contain a variety of potentially pathogenic bacteria, fungi, antibiotic resistance genes, viruses, endotoxins, and toxic metal(loid)s. These potentially pathogenic substances spread with the bioaerosols, thereby posing health risks to workers and residents in and around the WWTP. Inhalation has been identified as the main exposure route, and children are at a higher risk of this than adults. Future studies should identify emerging contaminants, establish health risk assessments, and develop prevention and control systems.
The succession of bacterial and fungal populations was assessed in an activated sludge (AS) diffusion bioreactor treating a synthetic malodorous emission containing H2S, toluene, butanone and alpha-pinene. Microbial community characteristics (bacterial and fungal diversity, richness, evenness and composition) and bioreactor function relationships were evaluated at different empty bed residence times (EBRTs) and after process fluctuations and operational failures (robustness test). For H2S, butanone and toluene, the bioreactor showed a stable and efficient abatement performance regardless of the EBRT and fluctuations applied, while low alpha-pinene removals were observed. While no clear positive or negative relationship between community characteristics and bioreactor functions was observed, ecological parameters such as evenness and community dynamics seemed to be of importance for maintaining reactor stability. The optimal degree of evenness of the inoculum likely contributed to the high robustness of the system towards the fluctuations imposed. Actinobacteria, Proteobacteria and Fungi (Hypocreales, Chaeatothyriales) were the most abundant groups retrieved from the AS system with a putative key role in the degradation of butanone and toluene. Typical H2S and alpha-pinene degraders were not retrieved from the system. The inoculation of P. fluorescens, a known alpha-pinene degrader, to the system did not result in the enhancement of the degradation of this compound. This strain was likely outcompeted by the microorganisms already adapted to the AS environment.
