Biodegradation of alpha and beta endosulfan in broth medium and soil microcosm by bacterial strain Bordetella sp. B9

Unveiling six novel bacterial strains for fipronil and thiobencarb biodegradation: efficacy, metabolic pathways, and bioaugmentation potential in paddy soil

Introduction

Soil bacteria offer a promising approach to bioremediate pesticide contamination in agricultural ecosystems. This study investigated the potential of bacteria isolated from rice paddy soil for bioremediating fipronil and thiobencarb, common agricultural pesticides.

Methods

Bacterial isolates capable of degrading fipronil and thiobencarb were enriched in a mineral salt medium. A response surface methodology with a Box-Behnken design was utilized to optimize pesticide degradation with the isolated bacteria. Bioaugmentation tests were performed in paddy soils with varying conditions.

Results and discussion

Six strains, including single isolates and their mixture, efficiently degraded these pesticides at high concentrations (up to 800 µg/mL). Enterobacter sp., Brucella sp. (alone and combined), and a mixture of Stenotrophomonas sp., Bordetella sp., and Citrobacter sp. effectively degraded fipronil and thiobencarb, respectively. Notably, a single Pseudomonas sp. strain degraded a mixture of both pesticides. Optimal degradation conditions were identified as a slightly acidic pH (6-7), moderate pesticide concentrations (20-50 µg/mL), and a specific inoculum size. Bioaugmentation assays in real-world paddy soils (sterile/non-sterile, varying moisture) demonstrated that these bacteria significantly increased degradation rates (up to 14.15-fold for fipronil and 5.13-fold for thiobencarb). The study identifies these novel bacterial strains as promising tools for bioremediation and bioaugmentation strategies to tackle fipronil and thiobencarb contamination in paddy ecosystems.

Degradation and conversion of endosulfan by newly isolated Pseudomonas mendocina ZAM1 strain

Endosulfan contamination is one of the major concerns of soil ecosystem, which causes detrimental effects not only to humans but also to animals and plants. Therefore, the aim of this study was to isolate and identify a novel bacterial strain capable of degrading endosulfan in agriculture contaminated soils. A novel bacterial strain was isolated from the sugarcane field contaminated with endosulfan, and was named as ZAM1 strain. The ZAM1 bacterial strain was further identified as Pseudomonas mendocina based on the biochemical and molecular analysis. 16sRNA sequence analysis of ZAM1 strain shows maximum similarity with known endosulfan-degrading bacteria (Pseudomonas putida), respectively. Enrichment was carried out using the endosulfan as sole sulfur source. The ZAM1 strain was able to use α and β endosulfan as a sole sulfur source. Our results showed that ZAM1 strain degrades endosulfan >64.5% (50 mg/l) after 12 days of incubation. The residues were analyzed by GC-MS analysis and confirmed the formation of metabolites of dieldrin, 2 heptanone, methyl propionate, and endosulfan lactone compounds. Hence, these results indicate that the ZAM1 strain is a promising bacterial source for detoxification of endosulfan residues in the environment.

Biodegradation of α-endosulfan via hydrolysis pathway by Stenotrophomonas maltophilia OG2

Stenotrophomonas maltophilia OG2 was isolated from the intestine of cockroaches that was collected from a cow barn contaminated some pesticides belong to pyrethroid and organochlorine groups. OG2 was able to degrade α-endosulfan in non sulfur medium (NSM) as a sole sulfur source for growth within 10 days of incubation. The effects of some growth parameters on endosulfan biodegradation by OG2 was studied and found that the biodegradation was significantly affected by the endosulfan concentrations, pH and temperature. Experimental results obtained in different conditions show that the optimum concentration of α-endosulfan, pH and temperature were 100 mg/L, 8.0 and 30 °C, respectively. Under these conditions, the bacterium degraded 81.53% of the α-endosulfan after 10 days. The concentration of α-endosulfan and its metabolites was determined by HPLC. Endosulfan ether, endosulfan lactone and endosulfan diol were the main metabolites in culture, but did not produce toxic metabolite, endosulfan sulfate. These results suggested that S. maltophilia OG2 degrades α-endosulfan via a hydrolysis pathway. The present study indicates that strain OG2 may have potential use in the biodegradation of pesticides contaminated environments.

Threonine eliminylation by bacterial phosphothreonine lyases rapidly causes cross-linking of mitogen-activated protein kinase (MAPK) in live cells

Old long-lived proteins contain dehydroalanine (Dha) and dehydrobutyrine (Dhb), two amino acids engendered by dehydration of serines and threonines, respectively. Although these residues have a suspected role in protein cross-linking and aggregation, their direct implication has yet to be determined. Here, we have taken advantage of the ability of the enteropathogen Shigella to convert the phosphothreonine residue of the pT-X-pY consensus sequence of ERK and p38 into Dhb and followed the impact of dehydration on the fate of the two MAPKs. To that end, we have generated the first antibodies recognizing Dhb-modified proteins and allowing tracing them as they form. We showed that Dhb modifications accumulate in a long-lasting manner in Shigella-infected cells, causing subsequent formation of covalent cross-links of MAPKs. Moreover, the Dhb signal correlates precisely with the activation of the Shigella type III secretion apparatus, thus evidencing injectisome activity. This observation is the first to document a causal link between Dhb formation and protein cross-linking in live cells. Detection of eliminylation is a new avenue to phosphoproteome regulation in eukaryotes that will be instrumental for the development of type III secretion inhibitors.

Biodegradation of isoproturon by Pseudoxanthomonas sp. isolated from herbicide-treated wheat fields of Tarai agro-ecosystem, Pantnagar

A gram-negative, rod-shaped, isoproturon (IPU) utilizing bacterium was isolated from herbicide-applied wheat fields of Tarai agro-ecosystem, Pantnagar. The phylogenetic sequence analysis based on 16S rRNA sequence revealed that the isolate could be a distinct species within the genus Pseudomonas. The isolate was a close relative of Pseudoxanthomonas japonensis (95 % similarity) and designated as K2. The bacterial isolate showed positive reaction for oxidase, catalase, and 20 carbohydrates using KB009 Part A and B HiCarbohydrate™ Kit. Degradation experiments were conducted using 200 mg l^-1 initial IPU as a source of carbon at different pH and temperatures. Maximum IPU degradation by K2 was observed at pH 7.0 and 30 °C, while least degradation at 6.5 pH and 25 °C. Addition of dextrose along with IPU as an auxiliary carbon source increased IPU degradation by 4.72 %, as compared to the IPU degradation without dextrose under optimum conditions. 4-isopropylaniline was detected as a degradation by-product in the medium. The present study demonstrated the IPU metabolizing capacity of a novel bacterial isolate K2 that can be a better choice for the remediation of IPU-contaminated sites.

Isolation and Characterization of α-Endosulfan Degrading Bacteria from the Microflora of Cockroaches

Extensive applications of organochlorine pesticides like endosulfan have led to the contamination of soil and environments. Five different bacteria were isolated from cockroaches living in pesticide contaminated environments. According to morphological, physiological, biochemical properties, and total cellular fatty acid profile by Fatty Acid Methyl Esters (FAMEs), the isolates were identified as Pseudomonas aeruginosa G1, Stenotrophomonas maltophilia G2, Bacillus atrophaeus G3, Citrobacter amolonaticus G4 and Acinetobacter lwoffii G5. This is the first study on the bacterial flora of Blatta orientalis evaluated for the biodegradation of α-endosulfan. After 10 days of incubation, the biodegradation yields obtained from P. aeruginosa G1, S. maltophilia G2, B. atrophaeus G3, C. amolonaticus G4 and A. lwoffii G5 were 88.5% , 85.5%, 64.4%, 56.7% and 80.2%, respectively. As a result, these bacterial strains may be utilized for biodegradation of endosulfan polluted soil and environments.

Biodegradation of endosulfan isomers and its metabolite endosulfate by two biosurfactant producing bacterial strains of Bordetella petrii

The main objective of the investigation was to study the biodegradation of endosulfan isomers and its major metabolite endosulfate by two biosurfactant producing bacterial strains of Bordetella petrii. The significance of the study is to evaluate the capability of biosurfactant producing bacterial strains in enhancing the bioavailability of endosulfan. Sixty bacterial strains were isolated from the endosulfan degrading bacterial consortium and were screened for endosulfan degradation and biosurfactant production. Among those, two strains Bordetella petrii I GV 34 (Gene bank Accession No KJ02262) and Bordetella petrii II GV 36 (Gene bank Accession No KJ022625) were capable of degrading endosulfan with simultaneous biosurfactant production. Bordetella petrii I degraded 89% of α and 84% of β isomers of endosulfan whereas Bordetella petrii II degraded 82% of both the isomers. Both the strains were able to reduce the surface tension up to 19.6% and 21.4% with a minimum observed surface tension of 45 Dynes/cm and 44 Dynes/cm, respectively. The study revealed that the strains have the potential to enhance the degradation endosulfan residues in contaminated sites and water by biosurfactant production.

Isolation and identification of endosulfan-degrading bacteria and evaluation of their bioremediation in kor river, iran

Objectives

Endosulfan is a lipophilic insecticide, which causes severe health issues due to its environmental stability, toxicity, and biological reservation in organisms. It is found in the atmosphere, soil, sediments, surface waters, rain, and food in almost equal proportions. The aim of this study was to isolate and identify endosulfan-degrading bacteria from the Kor River and evaluate the possibility of applying bioremediation in reducing environmental pollution in the desired region.

Methods

Samples of surface sediments and water were collected from three different stations in two seasons (summer and autumn), as these are areas with high agricultural activity. Isolated bacteria were identified by various biochemical tests and morphological characteristics. The amounts of degradation of endosulfan isomers and metabolites produced as a result of biodegradation were then analyzed using gas chromatography/mass spectrometry.

Results

In this study, the following five bacterial genera were able to degrade endosulfan: Klebsiella, Acinetobacter, Alcaligenes, Flavobacterium, and Bacillus. During biodegradation, metabolites of endosulfan diol, endosulfan lactone, and endosulfan ether were also produced, but these had lesser toxicity compared with the original compound (i.e., endosulfan).

Conclusion

The five genera isolated can be used as a biocatalyst for bioremediation of endosulfan.

Biomineralization and formulation of endosulfan degrading bacterial and fungal consortiums

Microbial degradation offers an effective approach to remove toxicants and in this study, a microbial consortium consisting of bacterial strains and fungal strains were originally obtained from endosulfan contaminated agricultural soils. Identification of the bacterial isolates by 16S rRNA sequences revealed the isolates to be Halophilic bacterium JAS4, Klebsiella pneumoniae JAS8, Enterobacter asburiae JAS5, and Enterobacter cloacae JAS7, whereas the fungal isolates were identified by 18S rRNA sequences and the isolates were Botryosphaeria laricina JAS6, Aspergillus tamarii JAS9 and Lasiodiplodia sp. JAS12. The biodegradation of endosulfan was monitored by using HPLC and FTIR analysis. The bacterial and fungal consortium could degrade 1000 mg l(-1) of endosulfan efficiently in aqueous medium and in soil. The infrared spectrum of endosulfan degraded samples in the aqueous medium by bacterial and fungal consortium showed bands at 1400 and 950 cm(-1) which are the characteristics of COOH group and acid dimer band respectively. In the present investigation, low cost solid materials such as sawdust, soil, fly ash, molasses and nutrients were used for the formulation of microbial consortium and to achieve greater multiplication and survival of the microbial strains.

Biodegradation of endosulfan in broth medium and in soil microcosm by Klebsiella sp. M3

Nine endosulfan degrading bacterial strains were isolated by soil enrichment with endosulfan. Bacterial strain M3 was the most efficient degrader. Endosulfan degradation was accompanied by a decrease in pH of the medium and an increase in chloride ion concentration. The bacterium was tested for its ability to degrade endosulfan at different concentrations in broth and soil. Maximum degradation occurred at concentrations of 50 μg/ml of broth and 100 μg/g of soil. Values of Ks and Vmax were different for (α)- and (β)-endosulfan in broth. The kinetic indices (Vmax/Ks) for α-endosulfan and β-endosulfan were 0.051 and 0.048 day(-1) respectively, indicating that (α)-endosulfan was more rapidly degraded. Bacterial strain M3 was identified as Klebsiella sp. M3 on the basis of 16S rDNA sequence similarity (GenBank accession number JX273762).

Endosulfan induced alteration in bacterial protein profile and RNA yield of Klebsiella sp. M3, Achromobacter sp. M6, and Rhodococcus sp. M2

Three bacterial strains identified as Klebsiella sp. M3, Achromobacter sp. M6 and Rhodococcus sp. M2 were isolated by soil enrichment with endosulfan followed by shake flask enrichment technique. They were efficiently degrading endosulfan in the NSM (non sulfur medium) broth. Degradation of endosulfan was faster with the cell free extract of bacterial cells grown in the sulfur deficient medium (NSM) supplemented with endosulfan than that of nutrient rich medium (Luria Bertani). In the cell free extract of NSM supplemented with endosulfan as sole sulfur source, a unique band was visualized on SDS-PAGE but not with magnesium sulfate as the sole sulfur source in NSM and LB with endosulfan. Expression of a unique polypeptide band was speculated to be induced by endosulfan under sulfur starved condition. These unique polypeptide bands were identified as OmpK35 protein, sulfate binding protein and outer membrane porin protein, respectively, in Klebsiella sp. M3, Achromobacter sp. M6 and Rhodococcus sp. M2. Endosulfan showed dose dependent negative effect on total RNA yield of bacterial strains in nutrient rich medium. Absence of plasmid DNA indicated the presence of endosulfan metabolizing gene on genomic DNA.

Biodegradation of organochlorine pesticide endosulfan by bacterial strain Alcaligenes faecalis JBW4

The recently discovered endosulfan-degrading bacterial strain Alcaligenesfaecalis JBW4 was isolated from activated sludge. This strain is able to use endosulfan as a carbon and energy source. The optimal conditions for the growth of strain JBW4 and for biodegradation by this strain were identified, and the metabolic products of endosulfan degradation were studied in detail. The maximum level of endosulfan biodegradation by strain JBW4 was obtained using broth at an initial pH of 7.0, an incubation temperature of 40 degreeC and an endosulfan concentration of 100 mg/L. The concentration of endosulfan was determined by gas chromatography. Strain JBW4 was able to degrade 87.5% of alpha-endosulfan and 83.9% of beta-endosulfan within 5 days. These degradation rates are much higher than the previously reported bacterial strains. Endosulfan diol and endosulfan lactone were the major metabolites detected by gas chromatography-mass spectrometry; endosulfan sulfate, which is a persistent and toxic metabolite, was not detected. These results suggested that A. faecalis JBW4 degrades endosulfan via a non-oxidative pathway. The biodegradation of endosulfan by A. faecalis is reported for the first time. Additionally, the present study indicates that strain JBW4 may have potential for the biodegradation of endosulfan residues.

Mycoremediation of endosulfan and its metabolites in aqueous medium and soil by Botryosphaeria laricina JAS6 and Aspergillus tamarii JAS9

Microbial degradation offers an efficient and ecofriendly approach to remove toxicants from the contaminated environments. Botryosphaeria laricina JAS6 and Aspergillus tamarii JAS9 were capable of degrading endosulfan and their metabolites which were isolated through enrichment technique. Both the strains were able to withstand an exposure of 1300 mg/L and showed luxuriant growth at 1000 mg/L of endosulfan. The change in pH in the culture broth was from 6.8 to 3.4 and 3.8 during growth kinetic studies of JAS6 and JAS9 strains, respectively upon biological degradation of endosulfan. The degradation of endosulfan by JAS6 and JAS9 strains were examined by HPLC. The biodegradation rate constant (k) and the initial concentration were reduced by 50% (DT50) which was determined by first and pseudo first order kinetic models. In the present investigation it has been revealed that Botryosphaeria laricina JAS6 and Aspergillus tamarii JAS9 possessing endosulfan degrading capability are being reported for the first time. These findings confirm the degradation of endosulfan by JAS6 and JAS9 strains which were accompanied by significant reduction in the toxicity and could be used as remedial measure in contaminated environments.

Colonization of Alcaligenes faecalis strain JBW4 in natural soils and its detoxification of endosulfan

Alcaligenes faecalis strain JBW4, a strain of bacteria that is capable of degrading endosulfan, was inoculated into sterilized and natural soils spiked with endosulfan. JBW4 degraded 75.8 and 87.0 % of α-endosulfan and 58.5 and 69.5 % of β-endosulfan in sterilized and natural soils, respectively, after 77 days. Endosulfan ether and endosulfan lactone were the major metabolites that were detected by gas chromatography-mass spectrometry. This result suggested that A. faecalis strain JBW4 degrades endosulfan using a non-oxidative pathway in soils. The ability of strain JBW4 to colonize endosulfan-contaminated soils was confirmed by polymerase chain reaction-denaturing gradient gel electrophoresis. This result suggested that strain JBW4 competed with the original inhabitants in the soil to establish a balance and successfully colonize the soils. In addition, the detoxification of endosulfan by strain JBW4 was evaluated using single-cell gel electrophoresis and by determining the soil microbial biomass carbon and enzymatic activities. The results showed that the genotoxicity and ecotoxicity of endosulfan in soil were reduced after degradation. The natural degradation of endosulfan in soil is inadequate; therefore, JBW4 shows potential for the bioremediation of industrial soils that are contaminated with endosulfan residues.

Sorption of endosulphan sulphate in soil organic matter

Sorption of endosulphan sulphate in soil organic matter was investigated using Standard Elliot soil humic acid (HA) and soil fulvic acid (FA) at two ionic strengths (0.001 and 0.01). It was observed that divalent calcium ion and ionic strength affect the sorption of endosulphan sulphate in HA. All the experiments were carried out at pH 6.7 +/- 0.1. In the presence and absence of calcium (ionic strength 0.001), the solubility enhancement method was used to estimate the sorption coefficients of endosulphan sulphate in HA. For FA, the solubility enhancement method was used to estimate the sorption coefficients at an ionic strength of 0.001 (in the presence of calcium) and 0.01. The presence of calcium was found to significantly enhance (alpha = 0.01) the solubility of endosulphan sulphate in HA. Sorption coefficients at pH 6.7, obtained using the solubility enhancement method, were found to be 10-21 L/g in HA and 6 L/g in FA (in the presence of calcium). Increase in ionic strength from 0.001 to 0.01 decreased the sorption of endosulphan sulphate in HA. The effect of ionic strength and calcium on the sorption of endosulphan sulphate was most satisfactorily explained on the basis of the Donnan volume.

Isolation and characterization of a Pseudomonas sp. strain IITR01 capable of degrading α-endosulfan and endosulfan sulfate

AIM

To isolate bacteria capable of degrading endosulfan (ES) and the more toxic ES sulfate and to characterize their metabolites.

METHODS AND RESULTS

A Pseudomonas sp. strain IITR01 capable of degrading α-ES and toxic ES sulfate was isolated using technical-ES through enrichment culture techniques. No growth and no degradation were observed using β-ES. Thin-layer chromatography and gas chromatography-mass spectrum analysis revealed the disappearance of both α-ES and ES sulfate and the formation of hydroxylated products ES diol, ether and lactone. We show here for the first time the formation of aforementioned metabolites in contrast to ES hemisulfate yielded by an Arthrobacter sp. Metabolism of α-ES and endosulfate was also observed using the crude cell extract of IITR01. The molecular mass of protein induced during the degradation of α-ES and sulfate as substrate was found to be approximately 150 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).

CONCLUSION

We describe characterization of bacterium capable of degrading α-ES and ES sulfate but not β-ES. Genetic investigation suggests that a gene nonhomologous to the reported esd may be present in the strain IITR01.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study describes toxic ES degradation by a Pseudomonas species that may be utilized for the bioremediation of the industrial soils contaminated with ES residues.

Isolation of a novel gene encoding a 3,5,6-trichloro-2-pyridinol degrading enzyme from a cow rumen metagenomic library

3,5,6-trichloro-2-pyridinol (TCP) is a major metabolite of the insecticide chlorpyrifos and is hazardous to human and animal health. A gene encoding a TCP degrading enzyme was cloned from a metagenomic library prepared from cow rumen. The gene (tcp3A) is 2.5 kb in length, encoding a protein (Tcp3A) of 599 amino acid residues. Tcp3A has a potential signal sequence, as well as a putative ATP/GTP binding site, and a likely amidation site. The molecular weight of the enzyme is 62 kDa by SDS-PAGE. Comparison of Tcp3A with the NCBI database using BLASTP revealed homology to amidohydrolase proteins. Recombinant Escherichia coli harboring the tcp3A gene could utilize TCP as the sole source of carbon. TLC and HPLC revealed that TCP was degraded by recombinant E. coli harboring tcp3A. This is the first report of a gene encoding a TCP degrading enzyme.