Kegg Pathway: gamma-Hexachlorocyclohexane degradation

J Wildl Dis. 2008 Jul; 44(3): 664-9
Kroenlein KR, Sleeman JM, Holladay SD, Joyner PH, Brown JD, Griffin M, Saunders G, Smith SA

Previously, we reported that wild eastern box turtles (Terrapene carolina carolina) with aural abscesses contained higher body burdens of organochlorine (OC) compounds than those without the lesion. This lesion in captive chelonians is associated with turtles that are fed diets deficient in vitamin A. To examine the pathophysiology of this lesion and evaluate the relationship between OC burdens and vitamin A metabolism, we maintained red-eared sliders (Trachemys scripta elegans) under different conditions of OC exposure and dietary vitamin A concentrations from August 2005 to February 2006. Dietary vitamin A concentration (0 or 5 international units/g in the diet) and OC exposure (no OC compound or the mixture of 2 mg/kg chlordane, 0.25 mg/kg aroclor, and 1 mg/kg lindane) did not affect histologic score based on degree of squamous metaplasia of the tympanic epithelium or levels of plasma or liver vitamin A among the study groups. The results of this study suggest that 6 mo of exposure to the selected OC compounds, or similar duration of reduced dietary vitamin A concentrations do not influence the formation of squamous metaplasia and aural abscesses in red-eared sliders. Further studies are required to determine whether the duration of the experiment was insufficient, the OC compounds selected were inappropriate, the dosing was incorrect, and whether there are other unknown mechanisms causing the reported association between OC exposure and aural abscesses seen in eastern box turtles.

Fish Physiol Biochem. 2008 Mar; 34(1): 25-36
Singh PB, Singh V

This investigation was performed to monitor hexachlorocyclohexane isomers (HCHs), dichlorodiphenyltrichloroethane (DDT, and its metabolites, refered to as DDTs), plasma levels of estradiol-17beta (E2), and the gonadosomatic index (GSI) between sampling sites of unpolluted ponds of Gujartal, Jaunpur (control site) and the polluted rivers Gomti (Jaunpur) and Ganga (Varanasi), which affect the reproductive physiology of some edible catfish and carp during the pre-monsoon season. HCHs and DDTs were measured by gas liquid chromatography (GLC) and hormones by radioimmunoassay (RIA). The results indicated that the level of HCHs and DDTs was very high in both the catfish and the carp captured from the polluted rivers compared with the fish captured from the control site. The GSI and E2 values were lower in both groups of fish when compared to the fish from the control site. The results also indicate that catfish showed greater bioaccumulation of HCHs and DDTs than carp, above the permissible limit, as compared to the fish from the control site. In conclusion, fish from the Gomti and Ganga rivers were highly polluted when compared with fish from the control site, as was evident from high levels of tissue bioaccumulation of HCHs and DDTs and decreased levels of plasma E2, inhibiting the reproductive physiology of these species at the receptor level. The levels exceeded the maximum residue limits (MRL) as recommended by Codex, hence it is suggested that the fish should be avoided for food purposes.

J Agric Food Chem. 2008 Aug 13; 56(15): 6594-603
Raina V, Rentsch D, Geiger T, Sharma P, Buser HR, Holliger C, Lal R, Kohler HP

Technical hexachlorocyclohexane (HCH) and lindane are obsolete pesticides whose former production and use led to widespread contaminations posing serious and lasting health and environmental risks. Out of nine possible stereoisomers, alpha-, beta-, gamma-, and delta-HCH are usually present at contaminated sites, and research for a better understanding of their biodegradation has become essential for the development of appropriate remediation technologies. Because haloalkane dehalogenase LinB was recently found responsible for the hydroxylation of beta-HCH, delta-HCH, and delta-pentachlorocyclohexene (delta-PCCH), we decided to examine whether beta- and gamma-PCCH, which can be formed by LinA from alpha- and gamma-HCH, respectively, were also converted by LinB. Incubation of such substrates with Escherichia coli BL21 expressing functional LinB originating from Sphingobium indicum B90A showed that both beta-PCCH and gamma-PCCH were direct substrates of LinB. Furthermore, we identified the main metabolites as 3,4,5,6-tetrachloro-2-cyclohexene-1-ols and 2,5,6-trichloro-2-cyclohexene-1,4-diols by nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry. In contrast to alpha-HCH, gamma-HCH was not a substrate for LinB. On the basis of our data, we propose a modified gamma-HCH degradation pathway in which gamma-PCCH is converted to 2,5-cyclohexadiene-1,4-diol via 3,4,5,6-tetrachloro-2-cyclohexene-1-ol and 2,5,6-trichloro-2-cyclohexene-1,4-diol.

J Toxicol Environ Health A. 2008; 71(11-12): 703-9
Wittsiepe J, Schrey P, Lemm F, Eberwein G, Wilhelm M

Blood samples from 226 pregnant women aged between 19 and 41 yr, living in an industrialized area of Germany (Duisburg birth cohort study), were collected between September 2000 and November 2002 and analyzed for their content of persistent organic pollutants (POPs). Levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) were in the range of 4.34-97.3 pg WHO 1998 TEq/g(lipid base) (median: 25.96) or 3.77-63.56 pg WHO 2005 TEq/g(lipid base) (median: 19.38), respectively. Whole blood volume-based concentrations of organochlorine pesticides and their metabolites were 0.036-0.53 microg/L (median: 0.15) hexachlorobenzene (HCB), 4.5-1300 ng/L (median: 67) beta-hexachlorocyclohexane (HCH), 0.6-520 ng/L (median: 18) 4,4'-dichlorodiphenyltrichloroethane (DDT), and 0.1-9.1 microg/L (median: 0.54) 4,4'-dichlorodiphenyldichloroethene (DDE). Parameters influencing the POP levels in human blood were examined using multiple regression models. Levels and the levels scatter widths of most PCDD/F and PCB congeners and HCB increased significantly with age. Within the multiple regression model a weak age dependence was also found for beta-HCH and DDT, whereas blood levels of alpha- and gamma- HCH and DDE were not age dependent. The total lactation period for earlier born children decreased most POP blood levels, except for alpha- and gamma-HCH. Over the study period of 27 mo only a low decreasing effect on human POP blood levels was observed. The body mass index had in general no or a low positive influence on contaminant levels. Because exposure to PCDD/F and PCB is higher in most industrialized countries in comparison to less industrialized ones, lower levels of these substances were detected in blood samples of women who had lived outside Western Europe for a longer period. In contrast, these women showed higher blood levels of organochlorine pesticides, indicating that these chemicals are still in use outside Western Europe.

Br Poult Sci. 2008 May; 49(3): 290-8
MacLachlan DJ

1. Implementation of Good Manufacturing Practice and HACCP (Hazard Analysis Critical Control Points) in the production of poultry feed requires efficient tools for profiling risks associated with pesticide use in the production of crops for feed. 2. This paper describes a simple model that may be of use in the first tiers of risk profiling of feeds. 3. The model adequately reproduced the pattern of residues in fat and eggs of laying hens dosed with a selection of lipophilic pesticides that may be used in the production of crops for poultry feeds: deltamethrin, diflubenzuron, fipronil, lindane, piperonyl butoxide and spinosad. 4. Simulations suggest results derived from studies on laying chickens can be extrapolated to other laying birds. 5. Poultry meat production systems focus on maximising growth of birds giving rise to significant potential for dilution of residues that transfer to fat from feed. 6. Simulations of residues in fat of chickens, ducks, geese and turkeys exposed to a lipophilic pesticide with an elimination half-life of one day at 10 mg/kg body weight/d from hatching to typical market ages suggest residues in fat that are highest in turkeys > chickens > geese > ducks. 7. The model is of use in interpreting published dosing studies and predicting likely residues in birds at times after last exposure/dosing.

Bioresour Technol. 2008 Jun 16;
Abhilash PC, Singh N

In the present study we employed sugarcane bagasse for biotreatment of soil containing 50mgkg(-1) of lindane. Garden soil were treated with lindane and amended with varying concentrations of sugarcane bagasse (10%, 20%, 30%, 40% and 50%; w/w). Data on dissipation and degradation of lindane in soil columns (0-15, 15-30cm) were studied at six consecutive samplings (0, 3, 7, 45 and 60 days). Treatment with 50% sugarcane bagasse resulted in >53% degradation of lindane in upper soil column with minimal leaching to lower soil column (0.002%) while highest leaching of lindane from upper soil column to lower soil column was occurred in garden soil (35.8%). Similarly, a substantial microbial biomass input has detected in amended soil than garden soil. Our results provide evidence that sugarcane bagasse can accelerate lindane degradation by enhanced microbial activity and prevent pesticide mobility through soil column by adsorption. Sugarcane bagasse could be useful as cheaper, easy available alternative for the biotreatment of lindane impacted soil.

Toxicol Appl Pharmacol. 2008 Aug 15; 231(1): 10-6
Johri A, Yadav S, Dhawan A, Parmar D

Prenatal exposure to low doses of lindane has been shown to affect the ontogeny of xenobiotic metabolizing cytochrome P450s (CYPs), involved in the metabolism and neurobehavioral toxicity of lindane. Attempts were made in the present study to investigate the responsiveness of CYPs in offspring prenatally exposed to lindane (0.25 mg/kg b. wt.; 1/350th of LD(50); p. o. to mother) when challenged with 3-methylcholanthrene (MC) or phenobarbital (PB), inducers of CYP1A and 2B families or a sub-convulsant dose of lindane (30 mg/kg b. wt., p. o.) later in life. Prenatal exposure to lindane was found to produce an increase in the mRNA and protein expression of CYP1A1, 1A2, 2B1, 2B2 isoforms in brain and liver of the offspring at postnatal day 50. The increased expression of the CYPs in the offspring suggests the sensitivity of the CYPs during postnatal development, possibly, to low levels of lindane, which may partition into mother's milk. A higher increase in expression of CYP1A and 2B isoenzymes and their catalytic activity was observed in animals pretreated prenatally with lindane and challenged with MC (30 mg/kg, i. p.x5 days) or PB (80 mg/kg, i. p.x5 days) when young at age (approx. 7 weeks) compared to animals exposed to MC or PB alone. Further, challenge of the control and prenatally exposed offspring with a single sub-convulsant dose of lindane resulted in an earlier onset and increased incidence of convulsions in the offspring prenatally exposed to lindane have demonstrated sensitivity of the CYPs in the prenatally exposed offspring. Our data assume significance as the subtle changes in the expression profiles of hepatic and cerebral CYPs in rat offspring during postnatal development could modify the adult response to a later exposure to xenobiotics.

Chemosphere. 2008 Jun; 72(5): 781-4
Sosan MB, Akingbohungbe AE, Ojo IA, Durosinmi MA

The blood serum of cacao farmers and their domestic water sources were analyzed for insecticide residues in selected cacao growing communities of Southwestern Nigeria. The farmers were grouped into five exposure periods based on their years of involvement in insecticide application, viz, <5 years, 5-9 years, 10-14 years, 15-19 years and >20 years. The residue analyses revealed that 42 out of the 76 farmers had residues of diazinon, endosulfan, propoxur and lindane in their blood; and 47.6% out of these farmers belonged in the >20 years exposure duration period. About 34% of the farmers had diazinon with a mean concentration of 0.067 mg kg(-1), 29% endosulfan (mean=0.033 mg kg(-1)), 23% propoxur (mean=0.095 mg kg(-1)), and 17% lindane (mean=0.080 mg kg(-1)) in their blood. The residues of lindane, endosulfan and propoxur in all the exposure duration categories were found to be far below the no observable adverse effect level (NOAEL) while diazinon residues detected in the blood serum of the farmers in all the exposure duration categories exceeded the NOAEL of 0.02 mg kg(-1) for the insecticide. The study also revealed that the sources of drinking water had been contaminated with dazinon and propoxur in some of the farmers' localities; and the concentrations of the insecticides exceeded the acceptable daily intake (ADI). It is concluded that cacao farmers in Southwestern Nigeria may have been occupationally exposed due to insecticide application for mirid control in their cacao plantations; and the exposure at times is of such magnitude as to be hazardous to the farmers and their respective communities.

J Environ Sci Health B. 2008 May; 43(4): 307-13
Yang DB, Wang YQ, Liu WX, Tao S

Recent studies have focused on enantiomeric behaviors of chiral organochlorine pesticides (OCPs) in biotic matrix because they provide insights into the biotransformation processes of chiral OCPs. In the present paper, a double in-line column chromatographic method was developed to effectively remove the lipid impurity in different biotic samples for clean-up of OCPs. After an initial Soxhlet extraction of OCPs from the biotic samples by a mixture of acetone and dichloromethane (DCM), dimethyl sulfoxide (DMSO) was directly added to the extract, and low boiling point solvents (acetone and DCM) were then evaporated. OCPs remained in DMSO were eluted via column 1 filled with silicon gel, and subsequently passed through column 2 packed with 15% deactivated florisil. This novel method was characterized by significant time and solvent savings. The recovery rates of alpha-HCH (hexachlorocyclohexane), beta-HCH, gamma-HCH and delta-HCH were 78.5+/-3.1%, 72.4+/-7.7%, 72+/-4.0% and 70.0+/-8.7%, respectively, and 92.5+/-3.8%, 79.7+/-6.7% and 83.4+/-6.5% for 1,1-dichloro-2-(2-chlorophenyl)-2-(4- chlorophenyl) ethylene (o,p'-DDE), 1,1-dichloro-2-(2-chlorophenyl)-2-(4-chloro phenyl)ethane (o,p'-DDD) and 1,1,1-trichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl) ethane (o,p'-DDT), separately. In addition, the separation efficiencies of the target compounds by both achiral and chiral gas chromatographic columns were satisfactory using the established method. Therefore, the double in-line column chromatography was a useful alternative method for pretreatment of OCPs in different biotic samples.

Reprod Toxicol. 2008 Apr; 25(3): 316-26
Tiemann U

The present paper summarizes the toxicological data on the effects of the organochlorine pesticides DDT, its metabolites, TCPM, methoxychlor and lindane on folliculogenesis, ovulation, fertilization, and implantation of female reproductive organs in human, laboratory, and farm animals. These compounds possess the ability to disrupt endogenous hormone synthesis, storage or metabolism. Cells of the ovary, oviduct, and uterus are susceptible to the disruptive effects of organochlorine compounds (OCCs). This review discusses that the exposure to OCC causes an impairment of (1) female fertility by altering ovarian development and function and (2) implantation by altering endometrial function through their estrogenic activity. The main focus of this review is to provide an overview on data which support that assumption that OCC can substitute for estradiol in regulating the microanatomy of the female reproductive tract. The data indicate the potential of these compounds act as endocrine disrupting agents, but in a different extent.

Appl Microbiol Biotechnol. 2008 Jun; 79(4): 627-32
Fuchu G, Ohtsubo Y, Ito M, Miyazaki R, Ono A, Nagata Y, Tsuda M

gamma-Hexachlorocyclohexane (gamma-HCH) is a highly chlorinated pesticide that has caused serious environmental problems. Based on the frequently observed association of insertion sequence IS6100 with lin genes for gamma-HCH degradation in several gamma-HCH-degrading bacterial strains isolated to date, DNA fragments flanked by two copies of IS6100 were amplified by nested polymerase chain reaction (PCR) technique using a DNA sample extracted from soil contaminated with HCH. Four distinct DNA fragments with sizes of 6.6, 2.6, 1.6, and 1.3 kb were obtained, three of which carried lin genes: the 6.6-kb fragment carried linD and linE as well as linR; the 2.6-kb fragment showed a truncated form of linF; and the 1.6-kb fragment carried linB. Our approach, named as insertion sequence (IS)-based cassette PCR, was successful in the isolation of the lin genes from HCH-contaminated soil without cultivation of host cells and is applicable for the culture-independent isolation of other functional genes bordered by other IS elements.

Int J Syst Evol Microbiol. 2008 Apr; 58(Pt 4): 861-5
Kumar M, Verma M, Lal R

A Gram-negative, motile, rod-shaped and non-spore-forming bacterium was isolated from a soil sample collected from the area adjoining an India Pesticide Limited plant, Lucknow, India. Strain IPL18T was characterized on the basis of phenotypic and genotypic data. Based on 16S rRNA gene sequence analysis, this strain was shown to belong to genus Devosia, with highest sequence similarity of 97.5 % to Devosia riboflavina DSM 7230T. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequence analysis revealed that strain IPL18T shows an evolutionary relationship with Devosia neptuniae J1T. Strain IPL18T contains C18 : 1 omega 7c, 11-methyl C18 : 1 omega 7c and C16 : 0 as the major fatty acids along with 3-OH C18 : 0, characteristic of the genus Devosia. The branched-chain fatty acid iso-H C18 : 1 (4.69 %), not present in any of the Devosia species known so far, has been reported in strain IPL18T. The results of DNA-DNA hybridization experiments (13 % relatedness with D. riboflavina DSM 7230T and 11 % with D. neptuniae J1T), phylogenetic analysis and biochemical tests confirm that strain IPL18T represents a novel species of the genus Devosia for which the name Devosia chinhatensis sp. nov. is proposed. The type strain is IPL18T (=CCM 7426T=MTCC 8593T).

Phytother Res. 2008 Jul; 22(7): 902-6
Ahmed RS, Suke SG, Seth V, Chakraborti A, Tripathi AK, Banerjee BD

The protective effect of dietary feeding of Zingiber officinales Rosc. (ginger) against lindane-induced oxidative stress was investigated in male albino rats. Oxidative stress was monitored by estimating the extent of lipid peroxidation, activities of the oxygen free radical (OFR) scavenging enzymes superoxide dismutase (SOD) and catalase (CAT) and the status of the glutathione redox cycle antioxidants. Lindane administration (30 mg/kg bw orally for 4 weeks) was associated with enhanced lipid peroxidation and compromised antioxidant defenses in rats fed a normal diet. Concomitant dietary feeding of ginger (1%w/w) significantly attenuated lindane-induced lipid peroxidation, accompanied by modulation of OFR scavenging enzymes as well as reduced glutathione (GSH) and the GSH dependent enzymes glutathione peroxidase (Gpx), glutathione reductase (GR) and glutathione-S-transferase (GST) in these rats. These findings suggest that a diet containing naturally occurring compounds is effective in exerting protective effects by modulating oxidative stress.

Biosci Biotechnol Biochem. 2008 Mar; 72(3): 694-701
Wang Y, Shimodaira J, Miyasaka T, Morimoto S, Oomori T, Ogawa N, Fukuda M, Fujii T

To understand the response of soil bacteria to the surrounding environment, it is necessary to examine the gene expression profiles of the bacteria in the soil. For this purpose, we developed a new method of extracting RNA from soil reproducibly. Using this new method, we extracted RNA from a field soil, which was sterilized and inoculated with Rhodococcus sp. strain RHA1, a biphenyl degrader isolated from gamma-Hexachlorocyclohexane-contaminated soil. Data from agarose gel electrophoresis indicated that the extracted RNA was purified properly. This new method can be applied easily in the preparation of large amounts of RNA. Real-time reverse transcription-polymerase chain reaction (RT-PCR) experiments performed by the TaqMan method suggested that the bphAa gene in this strain, which is involved in the degradation of biphenyl, was induced in the biphenyl amended soil.

Food Chem Toxicol. 2008 May; 46(5): 1739-43
Radosavljević T, Mladenović D, Vucević D, Petrović J, Hrncić D, Djuric D, Loncar-Stevanović H, Stanojlović O

This study examines possible synergistic effects of lindane and ethanol on inducing liver injury and serum fatty acid derangement in adult male Wistar rats. When administered together, ethanol and lindane-induced even more pronounced increase of alanine aminotransferase (165 +/- 10 U/L) and gamma-glutamyltranspeptidase activity (10.3 +/- 0.6 U/L) than after isolated administration of either substance. In addition, separate administration of lindane and ethanol was followed by a significant decrease of linoleic acid level in the serum (301 +/- 38 mg/L, 276 +/- 35 mg/L vs. 416 +/- 48 mg/L). However, when ethanol administration was followed by lindane injection, serum linoleic acid was at the similar level found in the control group (516 +/- 62 mg/L). Ethanol-treated rats that received lindane 30 min after ethanol administration have shown a marked increase of palmitic (421 +/- 27 mg/L) and linolic acid level (43 +/- 5 mg/L) in comparison with rats that have been treated only with ethanol (316+/-26 mg/L for palmitic and 32 +/- 2 mg/L for linolic acid) or lindane (295 +/- 26 mg/L for palmitic and 301 +/- 38 mg/L for linolic acid). Linolic acid level was significantly greater in comparison with control group (29 +/- 1 mg/L). In conclusion, this study found enough evidence to support the hypothesis that acute ethanol intoxication potentiates lindane-induced liver injury and enhances lipid derangement.

J Endocrinol. 2008 Feb; 196(2): 399-412
Buteau-Lozano H, Velasco G, Cristofari M, Balaguer P, Perrot-Applanat M

Environmental chemicals may affect human health by disrupting endocrine function. Their possible role in the mammary gland and breast tumors is still unknown. Previous studies have demonstrated that vascular endothelial growth factor (VEGF), a key factor in angiogenesis and tumor progression, is an estrogen-regulated gene. We analyzed whether VEGF expression is regulated by different xenoestrogens in several breast cancer cells, MELN (derived from MCF-7) and MELP (derived from MDA-MB-231) and stably expressing estrogen receptor alpha (ERalpha); these cell lines stably express estrogen response element (beta-globin)-luciferase. Genistein, bisphenol A (BPA), 4-(tert-octyl)phenol (OP), dieldrin, and several phthalates, including benzyl butyl phthalate (BBP) and di-ethyl-2-hexyle phthalate (DEHP), were first shown to be estrogenic. These compounds induced a dose-dependent increase of VEGF secretion in MELN and MCF-7 cells; maximal effect was observed at 1-10 microM non-cytotoxic concentrations and was inhibited by the antiestrogen ICI 182 780. VEGF increase was not observed in ERalpha-negative MDA-MB-231 cells. Most substances increased VEGF transcript levels in MELN cells. In contrast, gamma-Hexachlorocyclohexane, vinclozolin, and the phthalates (mono-n-butyl ester phthalic acid, di-isononyle phthalate, and di-isodecyle phthalate) were ineffective on both VEGF secretion and estrogenic luciferase induction in these cell lines. Specific kinase inhibitors PD98059, SB203580, or LY294002 suppressed the xenoestrogen-induced VEGF response, suggesting activation of MEK, p38 kinase, and phosphatidylinositol-3-kinase pathways. Our in vitro results show for the first time that genistein and xenoestrogens (BPA, OP, dieldrin, BBP, and DEHP at high concentrations) up-regulate VEGF expression in MELN cells by an ER-dependent mechanism. Since VEGF increases capillary permeability and breast tumor angiogenesis in vivo, the physiological relevance of these findings is discussed.

Toxicology. 2008 Feb 28; 244(2-3): 190-7
Saradha B, Vaithinathan S, Mathur PP

Substantial evidence has piled up portending the adverse effects of environmental toxicants on male reproduction. Lindane, an organochlorine pesticide, has been reported to perturb testicular functions and hence fertility. To get more insight into the mechanism(s) involved in gonadal effect(s) of lindane, we sought to investigate whether treatment with lindane at a low dose would alter the levels of steroidogenic acute regulatory protein (StAR), androgen binding protein (ABP) and activities of steroidogenic enzymes (3beta-hydroxysteroid dehydrogenase and 17beta-hydroxysteroid dehydrogenase) in adult rat. Furthermore, the levels of H2O2 were monitored to delineate the possible role of H2O2 in mediating the testicular effects of lindane. Animals used for experimentation were divided into six groups and four animals were maintained in each group. Animals were administered with a single dose of lindane (5mg/kg body weight) and terminated at specific post-treatment intervals (0h, 3h, 6h, 12h, 24h and 72h) to analyze the early testicular response. Administration of lindane resulted in a sequential reduction in the levels of StAR and the activities of steroidogenic enzymes with a parallel increase in the levels of H2O2. These changes elicited by lindane were significant at 12h and 24h post-treatment. In case of ABP, a significant decline in the level was found at 12h after treatment. These findings demonstrate transient inhibitory effects of lindane on testicular steroidogenesis and the possible role of H2O2 in mediating these effects.

J Environ Sci Health B. 2008 Feb; 43(2): 157-71
Krishna KR, Philip L

In the present study, lindane (1,2,3,4,5,6-hexachlorocyclohexane), methyl parathion (O-dimethylO-(4-nitro-phenyl) phosphorothioate) and carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) degradation potential of different enriched bacterial cultures were evaluated under various environmental conditions. Enriched cultures behaved differently with different pesticides. degradation was more in a facultative anaerobic condition as compared to that in aerobic condition. A specific pesticide enriched culture showed maximum degradation of that pesticide irrespective of pesticides and environmental conditions. Lindane and endosulfan enriched cultures behaved almost similarly. degradation of lindane by lindane enriched cultures was 75 +/- 3% in aerobic co-metabolic process whereas 78 +/- 5% of lindane degradation occurred in anaerobic co-metabolic process. degradation of methyl parathion by methyl parathion enriched culture was 87 +/- 1% in facultative anaerobic condition. In almost all the cases, many intermediate metabolites were observed. However, many of these metabolites disappeared after 4-6 weeks of incubation. Mixed pesticide-enriched culture degraded all the three pesticides more effectively as compared to specific pesticide- enriched cultures. It can be inferred from the results that a bacterial consortium enriched with a mixture of all the possible pesticides that are present in the site seems to be a better option for the effective bioremediation of multi-pesticide contaminated site.

Chemosphere. 2008 Apr; 71(8): 1452-60
Georgi A, Trommler U, Reichl A, Kopinke FD

The effect of dissolved humic acid (HA) on two types of hydrolysis reactions was investigated: (I) dehydrochlorination of gamma-Hexachlorocyclohexane (HCH) and 1,1,2,2-tetrachloroethane (TeCA) as a reaction involving hydroxide ions (OH(-)) and (II) hydrolysis of 1-octyl acetate (OA) which is catalyzed by H(+) at the applied pH value (pH 4.5). The rate of TeCA hydrolysis was not affected by addition of 2 g l(-1) of HA at pH 10 (k' = 0.33 h(-1)) but HCH hydrolysis was significantly inhibited (k' = 4.6 x 10(-3) h(-1) without HA and 2.8 x 10(-3)h(-1) at 2 g l(-1) HA). HCH is sorbed by 51% whereas TeCA sorption is insignificant at this HA concentration. Sorbed HCH molecules are effectively protected due to electrostatic repulsion of OH(-) by the net negative charge of the HA molecules. In contrast, OA hydrolysis at pH 4.5 (k' = 1.6 x 10(-5) h(-1)) was drastically accelerated after addition of 2 g l(-1) HA (k' = 1.1 x 10(-3) h(-1)). The ratio of the pseudo-first-order rate constants of the sorbed and the freely dissolved ester fraction is about 70. H(+) accumulation in the microenvironment of the negatively charged HA molecules was suggested to contribute to the higher reaction rate for the sorbed fraction in case of this H(+)-catalyzed reaction. Analogous effects from anionic surfactants are known as micellar catalysis.

Arch Environ Contam Toxicol. 2008 Jan 29;
Sarkar SK, Binelli A, Riva C, Parolini M, Chatterjee M, Bhattacharya AK, Bhattacharya BD, Satpathy KK

This paper presents the first comprehensive report of the organochlorine pesticide residues (OCs) such as hexachlorocyclohexane isomers (HCHs), dichlorodiphenyltrichloroethane and its six metabolites (DDTs), and hexachlorobenzene (HCB) in core sediments (<63-mum particle size) from the Indian Sunderban wetland. The pooled mean values of the mass fraction of SigmaHCHs, HCB, and SigmaDDTs in the sediments were 0.05-12, 0.05-1.4, and 0.05-11.5 ng g(-1) dry weight, respectively. The vertical distribution of pesticides reveals an erratic pattern. The concentration of four isomers of HCHs reveals a heterogenic distribution where gamma-HCH (lindane) and beta-HCH shared the dominant part. The mass fraction of HCB did not show any sharp spatial variation. The prevailing sequence of DDT metabolites indicates an active degradation of the parent compound in the sediments and/or inputs of already degraded pp'DDT to the region. Peak concentrations of HCH isomers and DDT metabolites have the potential to induce ecotoxicological impact as per the sediment quality guidelines.