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Gi Seok Kwon - One of the best experts on this subject based on the ideXlab platform.
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Isolation of a soil bacterium capable of biodegradation and detoxification of Endosulfan and Endosulfan sulfate.
Journal of Agricultural and Food Chemistry, 2006Co-Authors: Ho Yong Sohn, Kee Sun Shin, Min-sub Jo, Ji-won Shin, Gi Seok KwonAbstract:Endosulfan, an endocrine disrupting chemical, is a widely used cyclodiene organochlorine pesticide worldwide, and it blocks neuronal GABAA-gated chloride channels in mammals and aquatic organisms. Endosulfan and its metabolites, such as Endosulfan sulfate, are persistent in environments and are considered as toxic chemicals. For bioremediation of Endosulfan, in this study, an attempt was made to isolate an Endosulfan and Endosulfan sulfate degrading bacterium from Endosulfan-polluted agricultural soil. Through repetitive enrichment and successive subculture using Endosulfan or Endosulfan sulfate as the sole carbon source, a bacterium KS-2P was isolated. The KS-2P was identified as Pseudomonas sp. on the basis of the results of a 16S rDNA sequencing analysis and MIDI test. The degradation ratios for Endosulfan or Endosulfan sulfate in minimal medium containing Endosulfan (23.5 μg mL-1) or Endosulfan sulfate (21 μg mL-1) were 52% and 71%, respectively. Our results suggest that Pseudomonas sp. KS-2P has pote...
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biodegradation of the organochlorine insecticide Endosulfan and the toxic metabolite Endosulfan sulfate by klebsiella oxytoca ke 8
Applied Microbiology and Biotechnology, 2005Co-Authors: Gi Seok Kwon, Ho Yong Sohn, Kee Sun ShinAbstract:Biodegradation of Endosulfan, a chlorinated cyclodiene insecticide, is generally accompanied by production of the more toxic and more persistent metabolite, Endosulfan sulfate. Since our reported Endosulfan degrader, Klebsiella pneumoniae KE-1, failed to degrade Endosulfan sulfate, we tried to isolate an Endosulfan sulfate degrader from Endosulfan-polluted soils. Through repetitive enrichment and successive subculture using mineral salt medium containing Endosulfan or Endosulfan sulfate as the sole source of carbon and energy, we isolated a bacterium capable of degrading Endosulfan sulfate as well as Endosulfan. The bacterium KE-8 was identified as Klebsiella oxytoca from the results of 16S rDNA sequence analysis. In biodegradation assays with KE-8 using mineral salt medium containing Endosulfan (150 mg l−1) or Endosulfan sulfate (173 mg l−1), the biomass was rapidly increased to an optical density at 550 nm of 1.9 in 4 days and the degradation constants for α- and β-Endosulfan, and Endosulfan sulfate were 0.3084, 0.2983 and 0.2465 day−1, respectively. Analysis of the metabolites further suggested that K. oxytoca KE-8 has high potential as a biocatalyst for bioremediation of Endosulfan and/or Endosulfan sulfate.
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induction of oxidative stress by Endosulfan and protective effect of lipid soluble antioxidants against Endosulfan induced oxidative damage
Toxicology Letters, 2004Co-Authors: Ho Yong Sohn, Chong Suk Kwon, Gi Seok KwonAbstract:Abstract The toxic mechanism of Endosulfan, a widely used organochlorine pesticide, was investigated in Saccharomyces cerevisiae and human cell lines. A concentration-dependent inhibition of cell growth was observed when S. cerevisiae was exposed to Endosulfan, and its cytotoxicity (IC50) was found to be 49 μM and 86 μM in HepG2 and HeLa human cell lines, respectively. The treatment of S. cerevisiae with Endosulfan resulted in oxidative damage, as demonstrated by thiobarbituric acid-reactive substance (TBARS) production, in a dose-dependent manner, and the growth inhibition was recovered by treatment with lipid-soluble antioxidants, such as α-tocopherol or β-carotene, suggesting that Endosulfan toxicity may be closely associated with Endosulfan-induced reactive oxygen species (ROS) generation. The inhibition of cellular respiration by Endosulfan treatment and the recovery of respiration activity by antioxidant treatment confirmed that Endosulfan induces oxidative stress and inhibits respiration via ROS generation. These results suggest that unicellular yeast might provide a useful system for elucidating the toxicity of Endosulfan.
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biotransformation of an organochlorine insecticide Endosulfan by anabaena species
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Ivan R Kennedy, Jongwoo Park, Gi Seok KwonAbstract:This study assesses the role of the blue-green algal species present in the soil in the dissipation of Endosulfan and its metabolites in the soil environment. Two Anabaena species, Anabaena sp. PCC 7120 and Anabaena flos-aquae, were used in this study. Anabaena sp. PCC 7120 produced three principal biotransformation compounds, chiefly Endosulfan diol (endodiol), and minor amounts of Endosulfan hydroxyether and Endosulfan lactone. Trace amounts of Endosulfan sulfate were detected. In comparison, the biotransformation of Endosulfan by Anabaena flos-aquae yielded mainly endodiol with minor amounts of Endosulfan sulfate. An unknown compound was produced up to 70% from Endosulfan spiked in the medium inoculated by A. flos-aquae after 8 days of incubation. Therefore, the Endosulfan fate was dependent on the species. Within 1 day of incubation, two Anabaena species produced low amounts of ‚-Endosulfan after application of R-Endosulfan. These results suggest the presence of isomerase in the Anabaena species. Further studies using a fermentor to control the medium pH at 7.4 to minimize chemical hydrolysis of Endosulfan revealed a major production of endodiol with minor amounts of Endosulfan sulfate and the unknown compound. These results showed that the production of the unknown compound might be dependent on the alkaline pH in the medium and that the production of endodiol by A. flos-aquae might be biologically controlled. This study showed that two algal species could contribute in the detoxification pathways of Endosulfan in the soil environment.
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klebsiella pneumoniae ke 1 degrades Endosulfan without formation of the toxic metabolite Endosulfan sulfate
Fems Microbiology Letters, 2002Co-Authors: Gi Seok Kwon, Ho Yong Sohn, Kee Sun ShinAbstract: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 μg Endosulfan ml−1 day−1 when incubated with 93.9 μg 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.
Noor S Shah - One of the best experts on this subject based on the ideXlab platform.
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comparative studies of various iron mediated oxidative systems for the photochemical degradation of Endosulfan in aqueous solution
Journal of Photochemistry and Photobiology A-chemistry, 2015Co-Authors: Noor S Shah, Xuexiang He, Javed Khan, Hasan M Khan, Dominic L Boccelli, Dionysios D DionysiouAbstract:Abstract This study investigated iron-mediated oxidative processes for the photochemical degradation of Endosulfan, a chlorinated insecticide and central nervous system disruptor. At UV fluence of 360 mJ/cm 2 , 52.4% and 32.0% removal of 2.45 μM initial Endosulfan was observed by UV/Fe 3+ and UV/Fe 2+ processes, respectively, at an initial concentration of 17.8 μM iron. The degradation of Endosulfan by UV/Fe 3+ or UV/Fe 2+ was dramatically enhanced by adding peroxide (i.e., H 2 O 2 , S 2 O 8 2− or HSO 5 − ). Among the UV/peroxide/Fe processes, the highest degradation efficiency of 99.0% at UV fluence of 360 mJ/cm 2 was observed by UV/HSO 5 − /Fe 2+ with 2.45 μM [Endosulfan] 0 , 17.8 μM [Fe 2+ ] 0 , and 49.0 μM [HSO 5 − ] 0 . The observed degradation rate constant of Endosulfan was promoted either by increasing [Fe 2+ ] 0 and/or [peroxide] 0 or by decreasing [Endosulfan] 0 , while the initial degradation rate of Endosulfan increased with increasing [Fe 2+ ] 0 , [peroxide] 0 , or [Endosulfan] 0 . At UV fluence of 6000 mJ/cm 2 , 45.0% mineralization as represented by the decrease in total organic carbon content was observed by UV/HSO 5 − /Fe 2+ at 9.80 μM [Endosulfan] 0 , 980 μM [HSO 5 − ] 0 , and 17.8 μM [Fe 2+ ] 0 . The major by-product of Endosulfan was observed in all cases to be Endosulfan ether which was further degraded with an extended reaction time. The results suggest that iron-mediated advanced oxidation processes (AOPs) have a high potential for the removal of Endosulfan and its by-product from contaminated water.
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kinetic and mechanism investigation on the gamma irradiation induced degradation of Endosulfan sulfate
Chemosphere, 2015Co-Authors: Noor S Shah, Javed Khan, Shah Nawaz, Mohammad Ismail, Kifayatullah Khan, Hasan M KhanAbstract:Abstract The gamma irradiation was investigated for potential removal of Endosulfan sulfate, an emerging water pollutant and central nervous system disruptor. A removal efficiency of 99.5% of initially 1.30 μM Endosulfan sulfate was observed at an absorbed dose of 1020 Gy. Aqueous electron (eaq−) was found to play primary role in the removal of Endosulfan sulfate which was possibly due to greater reactivity of eaq− with Endosulfan sulfate, considering the second-order rate constant of 8.1 × 109 and 3.4 × 1010 M−1 s−1 for hydroxyl radical ( OH) and eaq−, respectively, with Endosulfan sulfate. The removal efficiency of Endosulfan sulfate was affected by the pH of aqueous solution, with observed removal efficiency of 99.5%, 98.3% and 31.3% at pH 6.2, pH 10.0, and pH 2.6, respectively. The efficiency was also influenced by inorganic anions and humic acid in the order of nitrate > nitrite > bicarbonate > carbonate ≃ humic acid. The initial degradation rate increased while degradation constant decreased with increasing initial concentrations of Endosulfan sulfate. The degradation pathways showed that oxidative pathway was initiated at the SO2 bond while reductive pathways at the chlorine attached to the ring of Endosulfan sulfate. The mass balance showed removal of 98% chloride and 72% sulfate ions from Endosulfan sulfate at an absorbed dose of 1020 Gy. The removal of Endosulfan sulfate followed by subsequent loss of by-products under extended treatment showed that gamma irradiation is potential technique for the remediation of organic pollutants from a water environment.
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role of aqueous electron and hydroxyl radical in the removal of Endosulfan from aqueous solution using gamma irradiation
Journal of Hazardous Materials, 2014Co-Authors: Noor S Shah, Javed Khan, Shah Nawaz, Hasan M KhanAbstract:Abstract The removal of Endosulfan, an emerging water pollutant, from water was investigated using gamma irradiation based advanced oxidation and reduction processes (AORPs). A significant removal, 97% of initially 1.0 μM Endosulfan was achieved at an absorbed dose of 1020 Gy. The removal of Endosulfan by gamma-rays irradiation was influenced by an absorbed dose and significantly increased in the presence of aqueous electron (eaq−). However, efficiency of the process was inhibited in the presence of eaq− scavengers, such as N2O, NO3−, acid, and Fe3+. The observed dose constant decreased while radiation yield (G-value) increased with increasing initial concentrations of the target contaminant and decreasing dose-rate. The removal efficiency of Endosulfan II was lower than Endosulfan I. The degradation mechanism of Endosulfan by the AORPs was proposed showing that reductive pathways involving eaq− started at the chlorine attached to the ring while oxidative pathway was initiated due to attack of hydroxyl radical at the S O bond. The mass balance showed 95% loss of chloride from Endosulfan at an absorbed dose of 1020 Gy. The formation of chloride and acetate suggest that gamma irradiation based AORPs are potential methods for the removal of Endosulfan and its by-products from contaminated water.
Dileep K. Singh - One of the best experts on this subject based on the ideXlab platform.
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Identification of enzyme(s) capable of degrading Endosulfan and Endosulfan sulfate using in silico techniques
Enzyme and Microbial Technology, 2019Co-Authors: Ngangbam Sarat Singh, Ranju Sharma, Dileep K. SinghAbstract:Abstract Endosulfan is one of the most widely used organochlorine cyclodiene insecticides. Microbial oxidation of Endosulfan forms Endosulfan sulfate, which is more or less equally toxic and persistent as Endosulfan. Due to lack of specificity and efficiency of microbial bioremediation technique in the field conditions, enzymatic bioremediation is receiving huge attention to clean-up the environment. In the present study x-ray crystal structures of enzymes from Brookhaven Protein Data Bank were screened for their potential to degrade Endosulfan and Endosulfan sulfate using molecular docking and molecular dynamic simulation techniques. A phenol hydroxylase, 1PN0 from Trichosporon cutaneum was found to have potential to degrade both α-Endosulfan and Endosulfan sulfate while a bacterial CotA laccase from Bacillus subtilis , 3ZDW has the potential to degrade α-Endosulfan. The in silico result correlate with in vitro degradation study using two different strains of Trichosporon cutaneum . In vitro degradation study found that the fungal strain was capable of degrading 60.36 % α-Endosulfan, 70.73 % β-Endosulfanand 52.08% Endosulfan sulfate. The presence of phenol hydroxylase inhibitor in the sulfur free medium with Endosulfan and Endosulfan sulfate as sole sulfur source inhibits the growth of both the fungal strains. Such in silico techniques can provides an easy and reliable way to speed up the development of bioremediation processes through rapid identification of potential enzymes and microbes to counter the ever increasing number of toxic compounds in the environment.
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Biodegradation of Endosulfan and Endosulfan sulfate by Achromobacter xylosoxidans strain C8B in broth medium
Biodegradation, 2011Co-Authors: Ngangbam Sarat Singh, Dileep K. SinghAbstract: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 CO_2 from the culture media with Endosulfan as sulfur source as compared to MgSO_4 suggesting that the bacterial strain, Achromobacter xylosoxidans strain C8B probably degraded Endosulfan completely through the formation of Endosulfan ether.
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biodegradation of α and β Endosulfan by aspergillus sydoni
Chemosphere, 2009Co-Authors: Supriya Goswami, Dileep K. SinghAbstract:Abstract The biodegradation of Endosulfan and the metabolites formed were studied using fungi both in broth culture as well as in soil microcosm. Fungal strains were isolated from soil and grown in broth Czapek-dox medium. The strain which utilized Endosulfan and showed maximum growth was selected for detailed studies. Maximum degrading capability in shake flask culture was shown by Aspergillus sydoni which degraded 95% of Endosulfan α and 97% of Endosulfan β in 18 d of incubation. Soil microcosm study was also carried out using this strain in six different treatments. Endosulfan sulfate was the main metabolite formed along with small quantity of Endosulfan ether and Endosulfan lactone both in broth culture and soil microcosm. This isolated fungal strain will be a potential source for Endosulfan degrading enzymes and can be used for bioremediation at the contaminated sites.
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biodegradation of α and β Endosulfan in broth medium and soil microcosm by bacterial strain bordetella sp b9
Biodegradation, 2009Co-Authors: Supriya Goswami, Dileep K. SinghAbstract: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.
Hasan M Khan - One of the best experts on this subject based on the ideXlab platform.
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comparative studies of various iron mediated oxidative systems for the photochemical degradation of Endosulfan in aqueous solution
Journal of Photochemistry and Photobiology A-chemistry, 2015Co-Authors: Noor S Shah, Xuexiang He, Javed Khan, Hasan M Khan, Dominic L Boccelli, Dionysios D DionysiouAbstract:Abstract This study investigated iron-mediated oxidative processes for the photochemical degradation of Endosulfan, a chlorinated insecticide and central nervous system disruptor. At UV fluence of 360 mJ/cm 2 , 52.4% and 32.0% removal of 2.45 μM initial Endosulfan was observed by UV/Fe 3+ and UV/Fe 2+ processes, respectively, at an initial concentration of 17.8 μM iron. The degradation of Endosulfan by UV/Fe 3+ or UV/Fe 2+ was dramatically enhanced by adding peroxide (i.e., H 2 O 2 , S 2 O 8 2− or HSO 5 − ). Among the UV/peroxide/Fe processes, the highest degradation efficiency of 99.0% at UV fluence of 360 mJ/cm 2 was observed by UV/HSO 5 − /Fe 2+ with 2.45 μM [Endosulfan] 0 , 17.8 μM [Fe 2+ ] 0 , and 49.0 μM [HSO 5 − ] 0 . The observed degradation rate constant of Endosulfan was promoted either by increasing [Fe 2+ ] 0 and/or [peroxide] 0 or by decreasing [Endosulfan] 0 , while the initial degradation rate of Endosulfan increased with increasing [Fe 2+ ] 0 , [peroxide] 0 , or [Endosulfan] 0 . At UV fluence of 6000 mJ/cm 2 , 45.0% mineralization as represented by the decrease in total organic carbon content was observed by UV/HSO 5 − /Fe 2+ at 9.80 μM [Endosulfan] 0 , 980 μM [HSO 5 − ] 0 , and 17.8 μM [Fe 2+ ] 0 . The major by-product of Endosulfan was observed in all cases to be Endosulfan ether which was further degraded with an extended reaction time. The results suggest that iron-mediated advanced oxidation processes (AOPs) have a high potential for the removal of Endosulfan and its by-product from contaminated water.
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kinetic and mechanism investigation on the gamma irradiation induced degradation of Endosulfan sulfate
Chemosphere, 2015Co-Authors: Noor S Shah, Javed Khan, Shah Nawaz, Mohammad Ismail, Kifayatullah Khan, Hasan M KhanAbstract:Abstract The gamma irradiation was investigated for potential removal of Endosulfan sulfate, an emerging water pollutant and central nervous system disruptor. A removal efficiency of 99.5% of initially 1.30 μM Endosulfan sulfate was observed at an absorbed dose of 1020 Gy. Aqueous electron (eaq−) was found to play primary role in the removal of Endosulfan sulfate which was possibly due to greater reactivity of eaq− with Endosulfan sulfate, considering the second-order rate constant of 8.1 × 109 and 3.4 × 1010 M−1 s−1 for hydroxyl radical ( OH) and eaq−, respectively, with Endosulfan sulfate. The removal efficiency of Endosulfan sulfate was affected by the pH of aqueous solution, with observed removal efficiency of 99.5%, 98.3% and 31.3% at pH 6.2, pH 10.0, and pH 2.6, respectively. The efficiency was also influenced by inorganic anions and humic acid in the order of nitrate > nitrite > bicarbonate > carbonate ≃ humic acid. The initial degradation rate increased while degradation constant decreased with increasing initial concentrations of Endosulfan sulfate. The degradation pathways showed that oxidative pathway was initiated at the SO2 bond while reductive pathways at the chlorine attached to the ring of Endosulfan sulfate. The mass balance showed removal of 98% chloride and 72% sulfate ions from Endosulfan sulfate at an absorbed dose of 1020 Gy. The removal of Endosulfan sulfate followed by subsequent loss of by-products under extended treatment showed that gamma irradiation is potential technique for the remediation of organic pollutants from a water environment.
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role of aqueous electron and hydroxyl radical in the removal of Endosulfan from aqueous solution using gamma irradiation
Journal of Hazardous Materials, 2014Co-Authors: Noor S Shah, Javed Khan, Shah Nawaz, Hasan M KhanAbstract:Abstract The removal of Endosulfan, an emerging water pollutant, from water was investigated using gamma irradiation based advanced oxidation and reduction processes (AORPs). A significant removal, 97% of initially 1.0 μM Endosulfan was achieved at an absorbed dose of 1020 Gy. The removal of Endosulfan by gamma-rays irradiation was influenced by an absorbed dose and significantly increased in the presence of aqueous electron (eaq−). However, efficiency of the process was inhibited in the presence of eaq− scavengers, such as N2O, NO3−, acid, and Fe3+. The observed dose constant decreased while radiation yield (G-value) increased with increasing initial concentrations of the target contaminant and decreasing dose-rate. The removal efficiency of Endosulfan II was lower than Endosulfan I. The degradation mechanism of Endosulfan by the AORPs was proposed showing that reductive pathways involving eaq− started at the chlorine attached to the ring while oxidative pathway was initiated due to attack of hydroxyl radical at the S O bond. The mass balance showed 95% loss of chloride from Endosulfan at an absorbed dose of 1020 Gy. The formation of chloride and acetate suggest that gamma irradiation based AORPs are potential methods for the removal of Endosulfan and its by-products from contaminated water.
Ho Yong Sohn - One of the best experts on this subject based on the ideXlab platform.
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Isolation of a soil bacterium capable of biodegradation and detoxification of Endosulfan and Endosulfan sulfate.
Journal of Agricultural and Food Chemistry, 2006Co-Authors: Ho Yong Sohn, Kee Sun Shin, Min-sub Jo, Ji-won Shin, Gi Seok KwonAbstract:Endosulfan, an endocrine disrupting chemical, is a widely used cyclodiene organochlorine pesticide worldwide, and it blocks neuronal GABAA-gated chloride channels in mammals and aquatic organisms. Endosulfan and its metabolites, such as Endosulfan sulfate, are persistent in environments and are considered as toxic chemicals. For bioremediation of Endosulfan, in this study, an attempt was made to isolate an Endosulfan and Endosulfan sulfate degrading bacterium from Endosulfan-polluted agricultural soil. Through repetitive enrichment and successive subculture using Endosulfan or Endosulfan sulfate as the sole carbon source, a bacterium KS-2P was isolated. The KS-2P was identified as Pseudomonas sp. on the basis of the results of a 16S rDNA sequencing analysis and MIDI test. The degradation ratios for Endosulfan or Endosulfan sulfate in minimal medium containing Endosulfan (23.5 μg mL-1) or Endosulfan sulfate (21 μg mL-1) were 52% and 71%, respectively. Our results suggest that Pseudomonas sp. KS-2P has pote...
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biodegradation of the organochlorine insecticide Endosulfan and the toxic metabolite Endosulfan sulfate by klebsiella oxytoca ke 8
Applied Microbiology and Biotechnology, 2005Co-Authors: Gi Seok Kwon, Ho Yong Sohn, Kee Sun ShinAbstract:Biodegradation of Endosulfan, a chlorinated cyclodiene insecticide, is generally accompanied by production of the more toxic and more persistent metabolite, Endosulfan sulfate. Since our reported Endosulfan degrader, Klebsiella pneumoniae KE-1, failed to degrade Endosulfan sulfate, we tried to isolate an Endosulfan sulfate degrader from Endosulfan-polluted soils. Through repetitive enrichment and successive subculture using mineral salt medium containing Endosulfan or Endosulfan sulfate as the sole source of carbon and energy, we isolated a bacterium capable of degrading Endosulfan sulfate as well as Endosulfan. The bacterium KE-8 was identified as Klebsiella oxytoca from the results of 16S rDNA sequence analysis. In biodegradation assays with KE-8 using mineral salt medium containing Endosulfan (150 mg l−1) or Endosulfan sulfate (173 mg l−1), the biomass was rapidly increased to an optical density at 550 nm of 1.9 in 4 days and the degradation constants for α- and β-Endosulfan, and Endosulfan sulfate were 0.3084, 0.2983 and 0.2465 day−1, respectively. Analysis of the metabolites further suggested that K. oxytoca KE-8 has high potential as a biocatalyst for bioremediation of Endosulfan and/or Endosulfan sulfate.
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induction of oxidative stress by Endosulfan and protective effect of lipid soluble antioxidants against Endosulfan induced oxidative damage
Toxicology Letters, 2004Co-Authors: Ho Yong Sohn, Chong Suk Kwon, Gi Seok KwonAbstract:Abstract The toxic mechanism of Endosulfan, a widely used organochlorine pesticide, was investigated in Saccharomyces cerevisiae and human cell lines. A concentration-dependent inhibition of cell growth was observed when S. cerevisiae was exposed to Endosulfan, and its cytotoxicity (IC50) was found to be 49 μM and 86 μM in HepG2 and HeLa human cell lines, respectively. The treatment of S. cerevisiae with Endosulfan resulted in oxidative damage, as demonstrated by thiobarbituric acid-reactive substance (TBARS) production, in a dose-dependent manner, and the growth inhibition was recovered by treatment with lipid-soluble antioxidants, such as α-tocopherol or β-carotene, suggesting that Endosulfan toxicity may be closely associated with Endosulfan-induced reactive oxygen species (ROS) generation. The inhibition of cellular respiration by Endosulfan treatment and the recovery of respiration activity by antioxidant treatment confirmed that Endosulfan induces oxidative stress and inhibits respiration via ROS generation. These results suggest that unicellular yeast might provide a useful system for elucidating the toxicity of Endosulfan.
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klebsiella pneumoniae ke 1 degrades Endosulfan without formation of the toxic metabolite Endosulfan sulfate
Fems Microbiology Letters, 2002Co-Authors: Gi Seok Kwon, Ho Yong Sohn, Kee Sun ShinAbstract: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 μg Endosulfan ml−1 day−1 when incubated with 93.9 μg 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.