Role of Plasmid in Pesticide Degradation and Metal Tolerance in Two Plant Growth-Promoting Rhizobacteria Bacillus cereus (NCIM 5557) and Bacillus safensis (NCIM 5558). - Related Documents




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611501.0000Role of Plasmid in Pesticide Degradation and Metal Tolerance in Two Plant Growth-Promoting Rhizobacteria Bacillus cereus (NCIM 5557) and Bacillus safensis (NCIM 5558). Disha A (Bacillus cereus) and Disha B (Bacillus safensis) were isolated from pesticide-infested agricultural field and showed tolerance against pesticides, heavy metals, and antibiotics. The isolates exhibited PGPR activities in vitro as well as in field conditions in lentil (Lens culinaris) and cow pea (Vigna unguiculata). Both the Bacillus species could not be grown in mineral salt medium but efficiently grown in the media supplemented with pesticide (imidacloprid/carbendazim) demonstrating the utilization of pesticide as carbon/nitrogen source. The HPLC studies exhibited the pesticide (imidacloprid/carbendazim) degradation by both the bacteria. B. safensis showed better degradation of carbendazim (88.93%) and imidacloprid (82.48%) than that of B. cereus 78.07% and 49.12%, respectively. The bacterial isolates showed high concentration of heavy metal tolerance viz. lead, molybdenum, cadmium, copper, cobalt, and zinc, except mercury. Both the bacteria possessed single plasmid. The plasmid-cured isolates of B. cereus did not tolerate any pesticide, whereas that of B. safensis tolerated all the pesticides, like wild strains. The plasmid curing experiments did not affect the heavy metal tolerance ability of both the bacteria indicating the genomic nature of heavy metal tolerance genes, whereas pesticide resistance genes are plasmid-dependent in B. cereus but genomic in B. safensis.202235157142
609510.9993Isolation and characterization of plant growth promoting endophytic diazotrophic bacteria from Korean rice cultivars. We have isolated 576 endophytic bacteria from the leaves, stems, and roots of 10 rice cultivars and identified 12 of them as diazotrophic bacteria using a specific primer set of nif gene. Through 16S rDNA sequence analysis, nifH genes were confirmed in the two species of Penibacillus, three species of Microbacterium, three Bacillus species, and four species of Klebsiella. Rice seeds treated with these plant growth-promoting bacteria (PGPB) showed improved plant growth, increased height and dry weight and antagonistic effects against fungal pathogens. In addition, auxin and siderophore producing ability, and phosphate solubilizing activity were studied for the possible mechanisms of plant growth promotion. Among 12 isolates tested, 10 strains have shown higher auxin producing activity, 6 isolates were confirmed as strains with high siderophore producing activity while 4 isolates turned out to have high phosphate-solubilizing activity. These results strongly suggest that the endophytic diazotrophic bacteria characterized in this study could be successfully used to promote plant growth and inducing fungal resistance in plants.201423871145
609320.9990Arsenic-resistant and plant growth-promoting Firmicutes and γ-Proteobacteria species from industrially polluted irrigation water and corresponding cropland. AIMS: The aim of the study was to explore irrigation water polluted with industrial waste and corresponding cropland to screen bacteria for As detoxification and plant growth promotion. METHODS AND RESULTS: Plant growth-promoting (PGP) As-resistant cropland bacteria were isolated from contaminated irrigation water and corresponding agricultural soil. Phylogenetic analysis revealed that the isolates belonged to two distinct bacterial lineages; Firmicutes and γ-Proteobacteria. Maximum As(V) resistance was exhibited by Klebsiella pneumoniae T22 and Klebsiella oxytoca N53 (550 mmol l(-1) ), whereas maximum resistance against As(III) was exhibited by K. oxytoca N53 (200 mmol l(-1) ). Maximum As(V) reduction was shown by K. pneumoniae T22 (6·7 mmol l(-1) ), whereas maximum As(III) oxidation was exhibited by Bacillus subtilis T23 (4·8 mmol l(-1) ). As resistance genes arsB and ACR3 were detected in many of the isolates through polymerase chain reaction. Many of these isolates exhibited PGP traits such as hydrogen cyanide and auxin production as well as phosphate solubilization. The bacterial strains were able to enhance Triticum aestivum growth both in the absence and presence of As, and statistically significant increase in shoot and root lengths was observed especially in case of Acinetobacter lwoffii T24 and Citrobacter freundii N52-treated plants. CONCLUSIONS: Cropland bacteria have the ability to support plant growth. Bacteria of croplands irrigated with industrially polluted water develop resistance against toxicants. These bacteria are helpful for the plant growth in such contaminated lands. SIGNIFICANCE AND IMPACT OF THE STUDY: The bacteria capable of both As detoxification and plant growth promotion, such as A. lwoffii T24 and C. freundii N52, are ideal for remediation and reclamation of polluted lands for agriculture purposes.201728708308
623830.9990A novel glutamate-dependent acid resistance among strains belonging to the Proteeae tribe of Enterobacteriaceae. Morganella, Providencia and Proteus strains were capable of surviving pH 2.0 for 1 h if glutamate was present. These strains did not have glutamic acid decarboxylase activity and the gadAB genes were not detected in any of these bacteria. When exposed to pH 2.0 acid shocks, the survival rate of these bacteria was significantly increased with glutamate concentrations as low as 0.3 mM in the acid media. Escherichia coli cells incubated at pH 3.4 consumed four times more glutamate and produced at least 7-fold more gamma-amino butyric acid than Morganella, Providencia and Proteus strains. These results indicate that strains belonging to the Proteeae tribe might have novel glutamate dependent acid-resistance mechanisms.200415321677
611340.9989Metal tolerance assisted antibiotic susceptibility profiling in Comamonas acidovorans. Metal ions are known selective agents for antibiotic resistance and frequently accumulate in natural environments due to the anthropogenic activities. However, the action of metals that cause the antibiotic resistance is not known for all bacteria. The present work is aimed to investigate the co-selection of metals and antibiotic resistance in Comamonas acidovorans. Tolerance profile of 16 metals revealed that the strain could tolerate high concentrations of toxic metals i.e., Cr (710 ppm), As (380 ppm), Cd (320 ppm), Pb (305 ppm) and Hg (205 ppm). Additionally, metal tolerant phenotypes were subjected to antibiotic resistance profiling; wherein several metal tolerant phenotypes (Cr 1.35-fold; Co-1.33 fold; Mn-1.29 fold) were resistant, while other metal tolerant phenotypes (Mg 1.32-fold; Hg 1.29-fold; Cu 1.28-fold) were susceptible than control phenotype. Metal accumulation may alter the metabolism of C. acidovorans that activates or inactivates the genes responsible for antibiotic resistance, resulting in the resistance and/or susceptibility pattern observed in metal resistant phenotypes.201829302860
458650.9989Emergence of multi drug resistance among soil bacteria exposing to insecticides. Impacts of pesticide exposure on the soil microbial flora and cross resistance to antibiotics have not been well documented. Development of antibiotic resistance is a common issue among soil bacteria which are exposing to pesticides continuously at sub-lethal concentration. The present study was focused to evaluate the correlation between pesticide exposures and evolution of multi drug resistance among isolates collected from soil applied with insecticides. Twenty five insecticide (Monochrotophos) degrading bacteria were isolated from contaminated agricultural soil. The bacterial isolates Bacillus Sps, Bacillus cereus, Bacillus firmus and Bacillus thuringiensis were found to be resistant against chloramphenical, monochrotophos, ampicillin, cefotaxime, streptomycin and tetracycline antibiotics used. Involvement of plasmid in drug as well as insecticide resistant was confirmed through plasmid curing among selected bacterial strains. Bacillus Sps (MK-07), Bacillus cereus (MK-11), Bacillus firmus (MK-13) and Bacillus thuringiensis (MK-24) lost their resistant against insecticides and antibiotics once after removal of plasmid by exposing to 2% sodium dodecyl sulphate. The plasmid was transformed back to bacteria which produced similar derivatives when cultured in Minimal Salt medium (pH 7.0) supplemented with 0.4% of insecticide. Homology modeling was used to prove that organophosphorus hydrolase and able to metabolize all the antibiotics showed positive interaction with high docking score. The present study revealed that persistent of insecticides in the agricultural soil may lead to increasing development of multidrug resistance among soil bacteria.201728192223
607160.9989Functional properties of novel protective lactic acid bacteria and application in raw chicken meat against Listeria monocytogenes and Salmonella enteritidis. In this study 635 lactic acid bacteria of food origin were evaluated for their potential application as protective cultures in foods. A stepwise selection method was used to obtain the most appropriate strains for application as protective cultures in chicken meat. Specifically, all strains were examined for antimicrobial activity against various Gram positive and Gram negative pathogenic and spoilage bacteria. Strains exhibiting anti-bacterial activity were subsequently examined for survival in simulated food processing and gastrointestinal tract conditions, such as high temperatures, low pH, starvation and the presence of NaCl and bile salts. Selected strains where then examined for basic safety properties such as antibiotic resistance and haemolytic potential, while their antimicrobial activity was further investigated by PCR screening for possession of known bacteriocin genes. Two chosen strains were then applied on raw chicken meat to evaluate their protective ability against two common food pathogens, Listeria monocytogenes and Salmonella enteritidis, but also to identify potential spoilage effects by the application of the protective cultures on the food matrix. Antimicrobial activity in vitro was evident against Gram positive indicators, mainly Listeria and Brochothrix spp., while no antibacterial activity was obtained against any of the Gram negative bacteria tested. The antimicrobial activity was of a proteinaceous nature while strains with anti-listerial activity were found to possess one or more bacteriocin genes, mainly enterocins. Strains generally exhibited sensitivity to pH 2.0, but good survival at 45 degrees C, in the presence of bile salts and NaCl as well as during starvation, while variable survival rates were obtained at 55 degrees C. None of the strains was found to be haemolytic while variable antibiotic resistance profiles were obtained. Finally, when the selected strains Enterococcus faecium PCD71 and Lactobacillus fermentum ACA-DC179 were applied as protective cultures in chicken meat against L. monocytogenes and S. enteritidis respectively, a significantly reduced growth of these pathogenic bacteria was observed. In addition, these two strains did not appear to have any detrimental effect on biochemical parameters related to spoilage of the chicken meat.200919249112
609670.9989Diversity of endophytic Pseudomonas in Halimione portulacoides from metal(loid)-polluted salt marshes. Phytoremediation assisted by bacteria is seen as a promising alternative to reduce metal contamination in the environment. The main goal of this study was to characterize endophytic Pseudomonas isolated from Halimione portulacoides, a metal-accumulator plant, in salt marshes contaminated with metal(loid)s. Phylogenetic analysis based on 16S rRNA and gyrB genes showed that isolates affiliated with P. sabulinigri (n = 16), P. koreensis (n = 10), P. simiae (n = 5), P. seleniipraecipitans (n = 2), P. guineae (n = 2), P. migulae (n = 1), P. fragi (n = 1), P. xanthomarina (n = 1), and Pseudomonas sp. (n = 1). Most of these species have never been described as endophytic. The majority of the isolates were resistant to three or more metal(loid)s. Antibiotic resistance was frequent among the isolates but most likely related to species-intrinsic features. Common acquired antibiotic resistance genes and integrons were not detected. Plasmids were detected in 43.6 % of the isolates. Isolates that affiliated with different species shared the same plasmid profile but attempts to transfer metal resistance to receptor strains were not successful. Phosphate solubilization and IAA production were the most prevalent plant growth promoting traits, and 20 % of the isolates showed activity against phytopathogenic bacteria. Most isolates produced four or more extracellular enzymes. Preliminary results showed that two selected isolates promote Arabidopsis thaliana root elongation. Results highlight the diversity of endophytic Pseudomonas in H. portulacoides from contaminated sites and their potential to assist phytoremediation by acting as plant growth promoters and as environmental detoxifiers.201627023813
48780.9989Chromosome-encoded inducible copper resistance in Pseudomonas strains. Nine Pseudomonas strains were selected by their high copper tolerance from a population of bacteria isolated from heavy-metal polluted zones. Copper resistance (Cu(r)) was inducible by previous exposure of cultures to subinhibitory amounts of copper sulfate. All nine strains possessed large plasmids, but transformation and curing results suggest that Cu(r) is conferred by chromosomal genes. Plasmid-less Pseudomonas aeruginosa PAO-derived strains showed the same level of Cu(r) as environmental isolates and their resistance to copper was also inducible. Total DNA from the environmental Pseudomonas, as well as from P. aeruginosa PAO strains, showed homology to a Cu(r) P. syringae cop probe at low-stringency conditions but failed to hybridize at high-stringency conditions.19958572680
358390.9989Transfer of a lincomycin-resistant plasmid between coagulase-negative staphylococci during soybean fermentation and mouse intestine passage. Staphylococcus equorum is a benign bacterium and the predominant species in high-salt fermented food. Some strains of S. equorum contain antibiotic-resistance plasmids, such as pSELNU1 that contains a lincosamide nucleotidyltransferase (lnuA) gene and confers resistance to lincomycin. Previously, we showed that pSELNU1 is transferred to other bacteria under laboratory growth conditions. However, it is not known if the plasmid can be transferred to other bacteria during food fermentation (in situ) or during passage through animal intestines (in vivo). In this study, we examined the in situ and in vivo transfer of pSELNU1 using Staphylococcus saprophyticus as a recipient. During soybean fermentation, pSELNU1 was transferred to S. saprophyticus at a rate of 1.9 × 10-5-5.6 × 10-6 per recipient in the presence of lincomycin. However, during passage through murine intestines, the plasmid was transferred at similar rates (1.3 × 10-5 per recipient) in the absence of lincomycin, indicating that the plasmid transfer is much more efficient under in vivo conditions. Based on these results, we conclude that it is prudent to examine food fermentation starter candidates for the presence of mobile genetic elements containing antibiotic resistance genes and to select candidates lacking these genes.201931132119
158100.9989Homology- and cross-resistance of Lactobacillus plantarum to acid and osmotic stress and the influence of induction conditions on its proliferation by RNA-Seq. In this study, homology- and cross-resistance of Lactobacillus plantarum L1 and Lactobacillus plantarum L2 to acid and osmotic stress were investigated. Meanwhile, its proliferation mechanism was demonstrated by transcriptomic analysis using RNA sequencing. We found that the homologous-resistance and cross-resistance of L. plantarum L1 and L. plantarum L2 increased after acid and osmotic induction treatment by lactic acid and sodium lactate solution in advance, and the survival rate of live bacteria was improved. In addition, the count of viable bacteria of L. plantarum L2 significantly increased cultivated at a pH 5.0 with a 15% sodium lactate sublethal treatment, compared with the control group. Further study revealed that genes related to membrane transport, amino acid metabolism, nucleotide metabolism, and cell growth were significantly upregulated. These findings will contribute to promote high-density cell culture of starter cultures production in the fermented food industry.202133945164
6114110.9989Uranium and other heavy metal resistance and accumulation in bacteria isolated from uranium mine wastes. Ten bacterial strains isolated from uranium mine wastes were characterized in terms of their uranium and other metal resistance and accumulation. 16S rRNA gene sequence analysis identified the strains as members of genera Bacillus, Serratia, and Arthrobacter. Strains were able to utilize various carbon sources, particularly aromatic hydrocarbons, grow at broad pH and temperature ranges and produce non specific acid phosphatase relevant for metal phosphate precipitation in contaminated environment. The isolates exhibited high uranium and other heavy metals (Ni, Co, Cu and Cd) resistance and accumulation capacities. Particularly, Arthrobacter sp. J001 and Bacillus sp. J003 were superior in terms of U resistance at low pH (pH 4.0) along with metals and actinides (U and Th) removal with maximum cell loading of 1088 μmol U, 1293 μmol Th, 425 μmol Cu, 305 μmol Cd, 377 μmol Zn, 250 μmol Ni g(-1) cell dry wt. Genes encoding P(1B)-type ATPases (Cu-CPx and Zn-CPx) and ABC transporters (nik) as catalytic tools for maintaining cellular metal homeostasis were detected within several Bacillus spp., with possible incidence of horizontal gene transfer for the later gene showing phylogenetic lineage to α Proteobacteria members. The study provides evidence on intrinsic abilities of indigenous bacteria from U-mine suitable for survival and cleaning up of contaminated mine sites.201222375546
8456120.9989Identification of genes required by Bacillus thuringiensis for survival in soil by transposon-directed insertion site sequencing. Transposon-directed insertion site sequencing was used to identify genes required by Bacillus thuringiensis to survive in non-axenic plant/soil microcosms. A total of 516 genetic loci fulfilled the criteria as conferring survival characteristics. Of these, 127 (24.6 %) were associated with uptake and transport systems; 227 loci (44.0 %) coded for enzymatic properties; 49 (9.5 %) were gene regulation or sensory loci; 40 (7.8 %) were structural proteins found in the cell envelope or had enzymatic activities related to it and 24 (4.7 %) were involved in the production of antibiotics or resistance to them. Eighty-three (16.1 %) encoded hypothetical proteins or those of unknown function. The ability to form spores was a key survival characteristic in the microcosms: bacteria, inoculated in either spore or vegetative form, were able to multiply and colonise the soil, whereas a sporulation-deficient mutant was not. The presence of grass seedlings was critical to colonisation. Bacteria labelled with green fluorescent protein were observed to adhere to plant roots. The sporulation-specific promoter of spo0A, the key regulator of sporulation, was strongly activated in the rhizosphere. In contrast, the vegetative-specific promoters of spo0A and PlcR, a pleiotropic regulator of genes with diverse activities, were only very weakly activated.201424310935
3582130.9989Investigating the transmissibility of tet(W) in bifidobacteria exposed to acid and bile stress. Transfer of antibiotic resistance genes from probiotic bacteria to pathogens poses a safety concern. Orally administered probiotics are exposed to stressful conditions during gastrointestinal transit. In this study, filter mating experiments were performed to investigate the potential role of exposure of Bifidobacterium isolates to acid and bile stress on the transfer of a tetracycline resistance gene, tet(W), to Enterococcus faecalis ATCC 51299. No E. faecalis transconjugants were obtained after mating with either stressed or unstressed Bifidobacterium, thereby suggesting that tet(W) could not be transferred as a result of exposure to gastrointestinal stresses.201829662736
6753140.9989Survival of subsurface microorganisms exposed to UV radiation and hydrogen peroxide. Aerobic and microaerophilic subsurface bacteria were screened for resistance to UV light. Contrary to the hypothesis that subsurface bacteria should be sensitive to UV light, the organisms studied exhibited resistance levels as efficient as those of surface bacteria. A total of 31% of the aerobic subsurface isolates were UV resistant, compared with 26% of the surface soil bacteria that were tested. Several aerobic, gram-positive, pigmented, subsurface isolates exhibited greater resistance to UV light than all of the reference bacterial strains tested except Deinococcus radiodurans. None of the microaerophilic, gram-negative, nonpigmented, subsurface isolates were UV resistant; however, these isolates exhibited levels of sensitivity similar to those of the gram-negative reference bacteria Escherichia coli B and Pseudomonas fluorescens. Photoreactivation activity was detected in three subsurface isolates, and strain UV3 exhibited a more efficient mechanism than E. coli B. The peroxide resistance of four subsurface isolates was also examined. The aerobic subsurface bacteria resistant to UV light tolerated higher levels of H2O2 than the microaerophilic organisms. The conservation of DNA repair pathways in subsurface microorganisms may be important in maintaining DNA integrity and in protecting the organisms against chemical insults, such as oxygen radicals, during periods of slow growth.19938285661
3710150.9988Tolerance to various toxicants by marine bacteria highly resistant to mercury. Bacteria highly resistant to mercury isolated from seawater and sediment samples were tested for growth in the presence of different heavy metals, pesticides, phenol, formaldehyde, formic acid, and trichloroethane to investigate their potential for growth in the presence of a variety of toxic xenobiotics. We hypothesized that bacteria resistant to high concentrations of mercury would have potential capacities to tolerate or possibly degrade a variety of toxic materials and thus would be important in environmental pollution bioremediation. The mercury-resistant bacteria were found to belong to Pseudomonas, Proteus, Xanthomonas, Alteromonas, Aeromonas, and Enterobacteriaceae. All these environmental bacterial strains tolerant to mercury used in this study were capable of growth at a far higher concentration (50 ppm) of mercury than previously reported. Likewise, their ability to grow in the presence of toxic xenobiotics, either singly or in combination, was superior to that of bacteria incapable of growth in media containing 5 ppm mercury. Plasmid-curing assays done in this study ascertained that resistance to mercury antibiotics, and toxic xenobiotics is mediated by chromosomally borne genes and/or transposable elements rather than by plasmids.200312876655
6112160.9988Analysis of heavy metal tolerance and genomics in an indigenous Kurthia strain from Kulik River reveals multi-metal resistance and dominance of selection pressure on codon usage patterns. Heavy metal(loid) contamination poses significant risks to biological entities and the ecosystem. Many metal(loid)-resistant bacteria have been isolated from different environmental sites, but still no work has described multi-metal resistant Kurthia sp. In this study, an indigenous Kurthia strain isolated from the surface water of River Kulik was studied to determine its level of tolerance to various metal(loid)s. This study aimed to isolate, characterize and determine the growth kinetics and efficiency of Kurthia gibsonii strain M6 to remove and bioaccumulate As(V), Ni and Pb in vitro. This study also aimed to sequence the whole genome of the bacterium, identify metal resistance genes and analyze the codon usage patterns and factors that affect the codon usage bias of these genes. The bacterium showed elevated resistance to As(V), Pb, Ni and Zn. Under metal(loid) stressed conditions, live cells of Kurthia strain M6 bioaccumulated 212.74, 91.51 and 40.38 mg g(-1) of As(V), Pb and Ni, respectively. The removal efficiency was 97%, 69.15% and 25.88% for Pb, Ni and As(V), respectively. Genome analysis revealed the existence of different genes conferring heavy metal resistance. A comprehensive analysis of codon usage patterns for metal resistance genes depicted the predominance of selection pressure as a prime force influencing codon usage patterns. This is the first time a multi-metal resistant K. gibsonii strain has been systematically studied regarding its heavy metal resistance biology. These findings will provide insights into the metal resistance mechanisms of the genus Kurthia and assist in devising new strategies for the bioremediation of metal-polluted environments.202539945867
6754170.9988Real-time PCR based analysis of metal resistance genes in metal resistant Pseudomonas aeruginosa strain J007. A uranium (U)-resistant and -accumulating Pseudomonas aeruginosa strain was characterized to assess the response of toxic metals toward its growth and expression of metal resistance determinants. The bacterium showed MIC (minimum inhibitory concentration) values of 6, 3, and 2 mM for Zn, Cu, and Cd, respectively; with resistance phenotype conferred by periplasmic Cu sequestering copA and RND type heavy metal efflux czcA genes. Real-time PCR-based expression analysis revealed significant upregulation of both these genes upon exposure to low concentrations of metals for short duration, whereas the global stress response gene sodA encoding superoxide dismutase enzyme was upregulated only at higher metal concentrations or longer exposure time. It could also be inferred that copA and czcA are involved in providing resistance only at low metal concentrations, whereas involvement of "global stress response" phenomenon (expression of sodA) at higher metal concentration or increased exposure was evident. This study provides significant understanding of the adaptive response of bacteria surviving in metal and radionuclide contaminated environments along with the development of real-time PCR-based quantification method of using metal resistance genes as biomarker for monitoring relevant bacteria in such habitats.201626662317
6074180.9988Beneficial properties of lactic acid bacteria naturally present in dairy production. BACKGROUND: Consumers are increasingly demanding for natural and beneficial foods, in order to improve their health and well-being. Probiotics play an important role in such demand, and dairy foods are commonly used as vehicles for such bacteria, represented predominantly by lactic acid bacteria. Due to consumers demand, food industry is constantly looking for novel bacterial strains, leading to studies that aims the isolation and characterization of their beneficial features. This study aimed to characterize the naturally occurring lactic acid bacteria obtained from a dairy environment, in order to assess their potential use as probiotics. RESULTS: Preliminary screening and PCR analysis, based on 16S rRNA sequencing, were applied to select and identify 15 LAB strains from the genera Lactobacillus (n = 11), Pediococcus (n = 2) and Weissella (n = 2). All strains showed resistance to low pH and the evaluated bile salt concentrations in vitro. The API ZYM test characterized the enzymatic activity of the strains, and a high β-galactosidase activity was observed in 13 strains. All strains presented resistance to simulated gastric (3 h) and intestinal (4 h) conditions in vitro, the ability to auto- and co-aggregate with indicator microorganisms and a high cell surface hydrophobicity. Most of the strains were positive for map and EFTu beneficial genes. All strains exhibited strong deconjugation of bile salts in vitro and all assimilated lactose. CONCLUSIONS: The phenotypes exhibited in vitro and the presence of beneficial genes revealed the beneficial potential of the studied strains, demanding further analyses in a food matrix and in vivo to allow the development of a functional product, with health-related properties.201830567551
3711190.9988Characterization of aerobic polycyclic aromatic hydrocarbon-degrading bacteria from Bizerte lagoon sediments, Tunisia. AIMS: To characterize polycyclic aromatic hydrocarbon (PAH)-degrading bacteria from sediments of the Bizerte lagoon, and to determine their ability to resist other pollutants such as antibiotics and heavy metals. METHODS AND RESULTS: More than 100 strains were isolated for their ability to use fluoranthene as the sole carbon and energy source. Most of them showed antibiotic and heavy metal resistance; 20 representative strains were selected for further analysis. 16S rRNA coding sequences analysis showed that the majority of the selected bacteria (75%) were affiliated to the Gammaproteobacteria. The selected strains also utilized high molecular weight PAHs containing up to four benzene rings and showed different profiles of PAH substrate usage suggesting different PAH degradation pathways. These results are consistent with the fact that nah-like genes and idoA-like genes, involved in PAH degradation, were detected in 6 and 1 strains respectively. CONCLUSIONS: The Bizerte lagoon, polluted by many human activities, leads to the co-selection of strains able to cope with multiple contaminants. SIGNIFICANCE AND IMPACT OF THE STUDY: Polluted areas are often characterized by the concomitant presence of organic pollutants, heavy metals and antibiotics. This study is one of the first showing bacterial strains adapted to multiple contaminants, a promising potential for the development of bioremediation processes.200817973912