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

Bacterial strains were isolated from endosulfan treated soil to study the microbial degradation of this pesticide in broth medium and soil microcosm. The isolates were grown in minimal medium and screened for endosulfan degradation. The strain, which utilized endosulfan and showed maximum growth, was selected for detail studies. Maximum degrading capability in shake flask culture was shown by Bordetella sp. B9 which degraded 80% of α endosulfan and 86% of β endosulfan in 18 days. Soil microcosm study was also carried out using this strain in six different treatments. Endosulfan ether and endosulfan lactone were the main metabolites in broth culture, while in soil microcosm endosulfan sulfate was also found along with endosulfan ether and endosulfan lactone. This bacterial strain has a potential to be used for bioremediation of the contaminated sites.     

Isolation and characterization of a Mycobacterium strain that metabolizes the insecticide endosulfan

AIM: The aim of this study was to isolate and characterize a bacterium capable of metabolizing endosulfan. METHODS AND RESULTS: A endosulfan-degrading bacterium (strain ESD) was isolated from soil inoculum after repeated culture with the insecticide as the sole source of sulfur. Analysis of its 16S rRNA gene sequence, and morphological and physiological characteristics revealed it to be a new fast-growing Mycobacterium, closely related to other Mycobacterium species with xenobiotic-degrading capabilities. Degradation of endosulfan by strain ESD involved both oxidative and sulfur-separation reactions. Strain ESD did not degrade endosulfan when sulfite, sulphate or methionine were present in the medium along with the insecticide. Partial degradation occurred when the culture was grown, with endosulfan, in the presence of MOPS (3-(N-morpholino)propane sulphonic acid), DMSO (dimethyl sulfoxide), cysteine or sulphonane and complete degradation occurred in the presence of gutathione. When both beta-endosulfan and low levels of sulphate were provided as the only sources of sulfur, biphasic exponential growth was observed with endosulfan metabolism being restricted to the latter phase of exponential growth. CONCLUSIONS: This study isolated a Mycobacterium strain (strain ESD) capable of metabolizing endosulfan by both oxidative and sulfur-separation reactions. The endosulfan-degrading reactions are a result of the sulfur-starvation response of this bacterium. SIGNIFICANCE AND IMPACT OF THE STUDY: This describes the isolation of a Mycobacterium strain capable of degrading the insecticide endosulfan. This bacterium is a valuable source of enzymes for use in enzymatic bioremediation of endosulfan residues.     

Biodegradation of organochlorine pesticide, endosulfan, by a fungal soil isolate, Aspergillus niger

Endosulfan is a chlorinated pesticide widely used in India for the protection of cotton, tea, sugarcane and vegetables. The persistence of endosulfan in environment and toxic effects on biota necessitate its removal. The role of soil fungi in recycling organic matter prompted us to attempt biodegradation of endosulfan using fungi. This study aims at enrichment, isolation and screening of fungi capable of metabolizing endosulfan. In all, 16 fungal isolates were obtained by enrichment of soil samples that had seems exposed to endosulfan before. Isolates were screened by a gradient plate assay, and results were confirmed by broth assay. On the basis of tolerance to endosulfan, an isolate, identified as Aspergillus niger was selected for further studies. The culture could tolerate 400 mg ml⁻¹ of technical grade endosulfan. Complete disappearance of endosulfan was seen on 12 days of incubation. Evolution of carbon dioxide during endosulfan metabolism has indicated the complete mineralization of endosulfan. Change in pH of culture broth to acidic range supported the biological transformation. Thin layer chromography (TLC) analyses revealed the formation of various intermediates of endosulfan metabolism including endosulfan diol, endosulfan sulfate, and an unidentified metabolite. The toxic intermediate, endosulfan sulfate, was also metabolized, further resulting in complete mineralization of endosulfan. Direct desulfurization of endosulfan sulfate or a novel pathway could be the mechanism of endosulfan and endosulfan sulfate degradation in Aspergillus niger. The fungal strain isolated by us could prove valuable for bioremediation of endosulfan contaminated soils and waters.     

Klebsiella pneumoniae KE-1 degrades endosulfan without formation of the toxic metabolite,endosulfan sulfate

For bioremediation of toxic endosulfan, endosulfan degradation bacteria, which do not form toxic endosulfan sulfate, were isolated from various soil samples using endosulfan as sole carbon and energy source. Among the 40 isolated bacteria, strain KE-1, which was identified as Klebsiella pneumoniae by physiological and 16S rDNA sequence analysis, showed superior endosulfan degradation activity. Analysis of culture pH, growth, free sulfate and endosulfan and its metabolites demonstrated that KE-1 biologically degrades 8.72 microg endosulfan ml(-1) day(-1) when incubated with 93.9 microg ml(-1) endosulfan for 10 days without formation of toxic endosulfan sulfate. Our results suggest that K. pneumoniae KE-1 degraded endosulfan by a non-oxidative pathway and that strain KE-1 has potential as a biocatalyst for endosulfan bioremediation.     

Effect of endosulfan on growth, alpha amylase activity and plasmids amplification in Bacillus subtilis

Endosulfan, a chlorinated hydrocarbon insecticide of cyclodiene subgroup acts as a contact poison in a wide variety of organisms. In the present study, the effect of endosulfan on the growth, alpha amylase activity and plasmid amplification was investigated in Bacillus subtilis system. The bacteria were grown in medium, incubated with different concentrations (32, 48, 64 and 80 microg/mL) of endosulfan. The bacterial growth was gradually seen after 1st day at up to 48 microg/L endosulfan. The 48 microg/L endosulfan inhibited approximately 50% of the bacterial growth. No growth was observed at and after 64 microg/L endosulfan, for all days (1-5). Also, no alpha amylase activity was found in the supernatant of the culture medium containing 64 and 80 microg/L endosulfan, whereas slight activity was observed with 32 and 48 microg/L endosulfan concentration. The amount of plasmid increased up to 50% in the presence of 32 microg/L endosulfan. Endosulfan had no effect on the alpha amylase activity in vitro.     

Studies on the genotoxicity of endosulfan in bacterial systems

Endosulfan, an organochlorine pesticide, was subjected to the differential sensitivity assay in repair-deficient and repair-proficient strains of Escherichia coli K12, prophage lambda induction assay in WP2s (lambda) and mutation induction in E. coli K12. The induction of umu gene expression with endosulfan was studied also in Salmonella typhimurium TA1535/pSK1002 cells. The differential sensitivity assay revealed that the recA 13 strain was the most sensitive. Endosulfan induced prophage lambda in E. coli and umu gene expression in S. typhimurium cells; however, the extent of the effects were low. Endosulfan also induced a dose-dependent increase in forward mutations in E. coli K12 cells from ampicillin sensitivity to ampicillin resistance. Our studies indicate the genotoxic potential of endosulfan and the role of the recA gene in the repair of endosulfan-induced DNA damage.     

Optimization of environmental parameters for biodegradation of alpha and beta endosulfan in soil slurry by Pseudomonas aeruginosa

Aim: To determine optimal environmental conditions for achieving biodegradation of α‐ and β‐endosulfan in soil slurries following inoculation with an endosulfan degrading strain of Pseudomonas aeruginosa. Methods and Results: Parameters that were investigated included soil texture, soil slurry: water ratios, initial inoculum size, pH, incubation temperature, aeration, and the use of exogenous sources of organic and amino acids. The results showed that endosulfan degradation was most effectively achieved at an initial inoculum size of 600 μl (OD = 0·86), incubation temperature of 30°C, in aerated slurries at pH 8, in loam soil. Under these conditions, the bacterium removed more than 85% of spiked α‐ and β‐endosulfan (100 mg l^?1) after 16 days. Abiotic degradation in noninoculated control medium within same incubation period was about 16%. Biodegradation of endosulfan varied in different textured soils, being more rapid in course textured soil than in fine textured soil. Increasing the soil contents in the slurry above 15% resulted in less biodegradation of endosulfan. Exogenous application of organic acids (citric acid and acetic acid) and amino acids (l ‐methionine and l ‐cystein) had stimulatory and inhibitory effects, respectively, on biodegradation of endosulfan. Conclusion: The results of this study demonstrated that biodegradation of endosulfan by Ps. aeruginosa in soil sediments enhanced significantly under optimized environmental conditions. Significance and Impact of the Study: Endosulfan is a commonly used pesticide that can contaminate soil, wetlands and groundwater. Our study demonstrates that bioaugmentation of contaminated soils with an endosulfan degrading bacterium under optimized conditions provides an effective bioremediation strategy.     

Degradation of lindane and endosulfan by fungi, fungal and bacterial laccases

The ability of two white-rot fungi (Trametes versicolor and Pleurotus ostreatus) and one brown-rot fungus (Gloeophyllum trabeum) to degrade two organochlorine insecticides, lindane and endosulfan, in liquid cultures was studied and dead fungal biomass was examined for adsorption of both insecticides from liquid medium. Lindane and endosulfan were also treated with fungal laccase and bacterial protein CotA, which has laccase activities. The amount of degraded lindane and endosulfan increased with their exposure period in the liquid cultures of both examined white-rot fungi. Endosulfan was transformed to endosulfan sulphate by T. versicolor and P. ostreatus. A small amount of endosulfan ether was also detected and its origin was examined. Degradation of lindane and endosulfan by a brown rot G. trabeum did not occur. Mycelial biomasses of all examined fungi have been found to adsorb lindane and endosulfan and adsorption onto fungal biomass should therefore be considered as a possible mechanism of pollutant removal when fungal degradation potentials are studied. Bacterial protein CotA performed more efficient degradation of lindane and endosulfan than fungal laccase and has shown potential for bioremediation of organic pollutants.     

Differential effects of chronic endosulfan exposure to male rats in relation to hepatic drug metabolism and androgen biotransformation

Chronic endosulfan exposure in rats led to considerable increase in the activities of drug metabolizing enzymes, whereas it had inhibitory effect on the activities of enzymes involved in the androgen biotransformation. Endosulfan also produced a dose- and duration-dependent increase in microsomal lipid peroxidation. The alterations produced after shorter duration showed much variation with respect to the dose levels and exposure period of endosulfan studied. The above biochemical changes were reversed after endosulfan withdrawal.     

Biodegradation of endosulfan and endosulfan sulfate by <Emphasis Type="Italic">Achromobacter xylosoxidans</Emphasis> strain C8B in broth medium

Endosulfan is one of the most widely used wide spectrum cyclodiene organochlorine insecticide. In environment, endosulfan can undergo either oxidation or hydrolysis reaction to form endosulfan sulfate and endosulfan diol respectively. Endosulfan sulfate is as toxic and as persistent as its parent isomers. In the present study, endosulfan degrading bacteria were isolated from soil through selective enrichment technique using sulfur free medium with endosulfan as sole sulfur source. Out of the 8 isolated bacterial strains, strain C8B was found to be the most efficient endosulfan degrader, degrading 94.12% α-endosulfan and 84.52% β-endosulfan. The bacterial strain was identified as Achromobacter xylosoxidans strain C8B on the basis of 16S rDNA sequence similarity. Achromobacter xylosoxidans strain C8B was also found to degrade 80.10% endosulfan sulfate using it as sulfur source. No known metabolites were found to be formed in the culture media during the entire course of degradation. Besides, the bacterial strain was found to degrade all the known endosulfan metabolites. There was marked increase in the quantity of released CO₂ from the culture media with endosulfan as sulfur source as compared to MgSO₄ suggesting that the bacterial strain, Achromobacter xylosoxidans strain C8B probably degraded endosulfan completely through the formation of endosulfan ether.     

Kinetics of Endosulfan Biodegradation by Stenotrophomonas maltophilia EN-1 Isolated From Pesticide-Contaminated Soil

Endosulfan is one of the persistent organochlorinated pesticides used extensively throughout the world, particularly in the developing countries. Its microbial metabolic transformation product endosulfan sulphate is more toxic and persistent than the parent compound itself. In order to completely mineralize endosulfan, augmentation of soil microbial community with efficient endosulfan degradation properties could a potentially viable option. In the present study, endosulfan degrading bacterium was isolated from the agriculture-contaminated soil of Shujaabad, Multan, Pakistan by using enrichment technique. The isolated bacterial strain EN-1 (Endosulfan-1) was identified as S. maltophilia by 16S rRNA sequencing and biochemical analysis. EN-1 has demonstrated the ability to utilize endosulfan as sole sulfur source. Kinetics of endosulfan degradation was studied at various initial concentrations ranges from 5 mg/L to 100 mg/L by growth dependent and growth independent kinetic models. Biodegradation kinetics revealed that the bacterium was highly efficient in endosulfan degradation. The average values of kinetic constants i.e. K_s, and µ_max were 13.73 mg/L and 0.210 h^?1 respectively, while µ_max/K_s ratio was 0.015. Addition of sulfur decreased the rate of degradation as the µ_max/K_s was observed to reduce. GC-MS analysis revealed that the bacterium metabolised the endosulfan into non-toxic metabolite i.e. endosulfan diol. The study instigates a complete elucidation of degradation process for commercial applications.     

Enhanced biodegradation of diesel oil by a newly identified Rhodococcus baikonurensis EN3 in the presence of mycolic acid

AIMS: The aim of the present study was to isolate and characterize a bacterium, strain EN3, capable of using diesel oil as a major carbon and energy source, and to analyse the enhancement of diesel oil degradation by this organism using synthetic mycolic acid (2-hexyl-3-hydroxyldecanoic acid). METHOD AND RESULTS: An actinomycete with the ability to degrade diesel oil was isolated from oil contaminated soil and characterized. The strain had phenotypic properties consistent with its classification in the genus Rhodococcus showing a 16S rRNA gene similarity of 99.7% with Rhodococcus baikonurensis DSM 44587(T). The ability of the characterized strain to degrade diesel oil at various concentrations (1000, 5000, 10 000 and 20 000 mg l(-1)) was determined. The effect of synthetic mycolic acid on the biodegradation of diesel oil was investigated at the 20 000 mg l(-1) concentration; the surfactant was added to the flask cultures at three different concentrations (10, 50 and 100 mg l(-1)) and degradation followed over 7 days. Enhanced degradation was found at all three concentrations of the surfactant. In addition, the enhancement of diesel oil degradation by other surfactants was observed. CONCLUSIONS: The synthetic mycolic acid has potential for the remediation of petroleum-contaminated sites from both an economic and applied perspective as it can stimulate biodegradation at low concentrations. SIGNIFICANCE AND IMPACT OF THE STUDY: This study showed that the synthesized mycolic acid can be used for potential applications in the bioremediation industries, for example, in oil spill clean-up, diesel fuel remediation and biostimulation.     

Biodegradability and biodegradation pathways of endosulfan and endosulfan sulfate

Endosulfan and endosulfan sulfate are persistent organic pollutants that cause serious environmental problems. Although these compounds are already prohibited in many countries, residues can be detected in soils with a history of endosulfan application. Endosulfan is transformed in the environment into endosulfan sulfate, which is a toxic and persistent metabolite. However, some microorganisms can degrade endosulfan without producing endosulfan sulfate, and some can degrade endosulfan sulfate. Therefore, biodegradation has the potential to clean up soil contaminated with endosulfan. In this review, we provide an overview of aerobic endosulfan degradation by bacteria and fungi, and a summary of recent advances and prospects in this research field.     

Biodegradation of di-n-butyl phthalate by Rhodococcus sp. JDC-11 and molecular detection of 3, 4-phthalate dioxygenase gene

Rhodococcus sp. JDC-11, capable of utilizing di-n-butyl phthalate (DBP) as the sole source of carbon and energy, was isolated from sewage sludge and confirmed mainly based on 16S rRNA gene sequence analysis. The optimum pH, temperature, and agitation rate for DBP degradation by Rhodococcus sp. JDC-11 was 8.0, 30 degrees C, and 175 rpm, respectively. In addition, the effect of glucose concentration on DBP degradation indicated that low concentration of glucose inhibited the degradation of DBP while high concentrations of glucose increased its degradation. Meanwhile, the substrates utilization test showed that JDC-11 could also utilize other phthalates. Furthermore, the major metabolites of DBP degradation were identified as mono-butyl phthalate and phthalic acid by gas chromatography-mass spectrometry and the metabolic pathway of DBP degradation by Rhodococcus sp. JDC-11 was tentatively speculated. Using a set of new degenerate primer, partial sequence of the 3, 4-phthalate dioxygenase gene was obtained from the strain. Sequence analysis revealed that the phthalate dioxygenase gene of JDC-11 was highly homologous to the large subunit of phthalate dioxygenase from Rhodococcus coprophilus strain G9.     

一株乙腈降解菌的鉴定及其生物学特性

【目的】明确乙腈降解菌BX2的分类地位及生物学特性,评价其处理含乙腈废水的可行性。【方法】通过形态特征、生理生化特性以及系统发育分析对菌株BX2进行鉴定。考察温度、初始pH及接种量等因素对菌株生长的影响,确定菌株的最佳生长条件及在该条件下的乙腈降解能力。测定菌株BX2对NaCl的耐受能力。【结果】乙腈降解菌BX2的形态特征及生理生化特性与紫红红球菌(Rhodococcus rhodochrous)最相近。其16S rRNA、gyrB、secA1基因序列与紫红红球菌的相似性分别为99.37%、99.29%、97.87%。最佳生长条件为35℃,初始pH 7.5,接种量1%。此条件下,菌株BX2在16 h内对浓度为800 mg/L乙腈的降解率为95.87%。菌株BX2在NaCl含量高于6%的培养基中无法生长。【结论】菌株BX2被鉴定为紫红红球菌。该菌株有较强的环境适应能力,可降解高浓度乙腈,在含氰废水的生物修复中有很好的应用前景。     

Isolation and characterization of a new Achromobacter sp. strain CAR1389 as a carbazole-degrading bacterium

In this work, a bacterial strain with suitable capability to metabolize carbazole (CAR) as a main nitrogen containing compound of petroleum was isolated and characterized. 16S rDNA gene analysis and morphological characteristics of the strain showed that the isolate belonged to the genus Achromobacter and was tentatively named as Achromobacter sp. strain CAR1389. The growth monitoring and biodegradation rate measurements of carbazole in minimal medium supplemented by 6?mM CAR revealed that the strain CAR1389 is able to remove more than 90?% of this compound at 25, 30, and 37?°C during 7?days. The effect of higher concentrations of the carbazole on growth rate and metabolizing activity of the strain exhibited the Achromobacter sp. strain CAR1389 can tolerate increasing levels of CAR concentration up to 21?mM in culture media and degrade 43?% of this toxic material. According to these results and high tolerance of this bacterium in regards to higher concentrations of CAR, we suggest the strain CAR1389 as a suitable isolate to do biorefining of crude oil and also bioremediation processes in highly contaminated area of carbazole.     

Endosulfan-enhanced crest induction in Daphnia longicephala: evidence for cholinergic innervation of kairomone receptors

Daphnia iongicephala were reared from early embryogenesis inthe presence or absence of crest-inducing kairomones releasedby Anisops gratus (Notonectidae) and from birth in one of fiveconcentrations of the organochiorine pesticide, endosulfan (0,0.1, 1.0, 10 or 100 g 1^–1 The morphologyof the daphnidswas measured 3 days after birth and on production of the firstbrood of eggs. The reproductive parameters, first brood size,age at first reproduction, mean egg volume and total egg volume,were also measured. Endosulfan significantly induced crest developmentin 3-day-old daphnids at 0.1, 1.0 and 10 g ^1– in thepresence and absence of Anisops kairomone, although crest sizein the absence of kairomone was only marginally greater thancontrols. A concentration of 10 pg 1^–1 endosulfan significantlyenhanced crest growth of kairomone-exposed daphnids at maturity.The Anisops kairomone alone induced a large crest in D.iongicephola,reduced first brood size, mean egg volume and total egg volume,and increased age at maturity. The coefficient of variationof mean egg volume was significantly reduced by Anisops kairomone.It is hypothesized that endosulfan enhances crest developmentbyinhibition of .     

Endosulfan Mineralization by Bacterial Isolates and Possible Degradation Pathway Identification

A bacterial consortium consists of three bacterial isolates, which rapidly mineralizes endosulfan, was enriched from an endosulfan-processing industrial surface soil. Batch experiments were conducted using bacterial consortium and its pure isolates for their potential degradation of endosulfan and its metabolites, i.e., endosulfan sulfate, endosulfan ether, and endosulfan lactone, in anaerobic condition. Endosulfan degradation was promising with bacterial consortium and pure isolates. Staphylococcus sp. preferably utilized beta endosulfan whereas other two Bacillus strains utilized more alpha endosulfan. The addition of supplementary carbon, i.e., dextrose, stimulated the endosulfan degradation efficiency in both the cases. Degradation of endosulfan ether and endosulfan lactone was promising with Bacillus circulans I and II whereas no endosulfan sulfate was degraded by any of these strains. From the present investigation, it was postulated that endosulfan was mineralized via hydrolysis pathway with the formation of carbenium ions and/or ethylcarboxylates, which later converted into simple hydrocarbons.     

Degradation of endosulfan during substrate preparation and cultivation of Pleurotus pulmonarius

Summary Endosulfan is an insecticide used on many vegetable crops. In mushroom cultivation, vegetable materials used as a growth substrate may contain residues of endosulfan that may accumulate in the final mushroom biomass. After preparing the substrate, it is subjected to pasteurization and/or composting and then inoculated with the desired fungus. The purpose of this research was to determine the rate and extent of endosulfan reduction from a grass substrate that was either composted or sterilized by autoclaving. In addition, the rate and extent of removal of endosulfan from substrate colonized with Pleurotus pulmonarius was determined. The degradation of 65 mg/kg endosulfan was analyzed on both, the substrate preparation and the culture of P. pulmonarius on the grass Digitaria decumbens. During composting in presence of Ca(OH)₂ for 120 h, the concentrations of α and β endosulfan were reduced by 61.4 and 49.5% respectively, significantly higher compared with the control (without Ca(OH)_2,) in which the reduction was 38.5%. After sterilization the concentration of α and β endosulfan was reduced by 84.8 and 87.5% respectively. After the colonization of substrate by P. pulmonarius (15 days after spawning) α and β endosulfan were reduced by 96% and at the end of cultivation (35 days after spawning) were reduced by 99%. When carpophores were analyzed, residues of α and β endosulfan were observed between 0.019–0.084 mg/kg. The results showed that α and β endosulfan were partially removed during the preparation of substrate and entirely eliminated during fungal colonization on the substrate.     

Suppression of auxin stimulated growth of barley coleoptile sections by endosulfan

Endosulfan, a cyclic sulphurous acid ester commonly used as a broad spectrum insecticide, suppressed the elongation of barley coleoptiles. Indoleacetic acid at optimum concentration overcame the inhibition of growth of coleoptiles treated with 10 ppm endosulfan. However, perfusion of the coleoptile sections with endosulfan and subsequent treatment with indoleacetic acid could not stimulate cell elongation to the extent observed in the control