Persistent ß-Hexachlorocyclohexane Exposure Impacts Cellular Metabolism with a Specific Signature in Normal Human Melanocytes.

BACKGROUND: Cutaneous melanoma arises from skin melanocytes and has a high risk of metastatic spread. Despite better prevention, earlier detection, and the development of innovative therapies, melanoma incidence and mortality increase annually. Major clinical risk factors for melanoma include fair skin, an increased number of nevi, the presence of dysplastic nevi, and a family history of melanoma. However, several external inducers seem to be associated with melanoma susceptibility such as environmental exposure, primarily unprotected sun experience, alcohol consumption, and heavy metals. In recent years, epidemiological studies have highlighted a potential risk of ß-hexachlorocyclohexane (ß-HCH), the most studied organochlorine pesticide, causing cancer induction including melanoma. METHODS: We evaluated in vitro the impact of this pollutant on epidermal and dermal cells, attempting to describe mechanisms that could render cutaneous cells more prone to oncogenic transformation. RESULTS: We demonstrated that ß-HCH impacts melanocyte biology with a highly cell-type specific signature that involves perturbation of AKT/mTOR and Wnt/ß-catenin signaling, and AMPK activation, resulting in lowering energy reserve, cell proliferation, and pigment production. CONCLUSIONS: In conclusion, long-term exposure to persistent organic pollutants damages melanocyte metabolism in its function of melanin production with a consequent reduction of melanogenesis indicating a potential augmented skin cancer risk.

Placental concentrations of xenoestrogenic organochlorine pesticides and polychlorinated biphenyls and assessment of their xenoestrogenicity in the PA-MAMI mother-child cohort.

BACKGROUND: Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCB), they have contributed to the exposure of women to persistent organic pollutants (POPs). These compounds can cross the placental barrier and interfere with the hormonal system of newborns. AIM: To determine concentrations of OCPs and PCBs and their xenoestrogenic activity in placentas of women from the PA-MAMI cohort of Panama. METHODS: Thirty-nine placenta samples from women in the Azuero peninsula (Panama) were analyzed. Five OCPs [p-p'-dichlorodiphenyldichloroethylene (p-p'-DDE), beta-hexachlorohexane (ß-HCH), γ-hexachlorohexane (lindane), hexachlorobenzene (HCB) and mirex] and three PCB congeners (PCB-138, PCB-153 and PCB-180) were quantified in placenta extracts. The xenoestrogenic activity of extracts was assessed with the E-Screen bioassay to estimate the total effective xenoestrogen burden (TEXB). RESULTS: All placental samples were positive for at least three POP residues and >70% for at least six. The frequencies of quantified OCPs ranged from 100% for p,p'-DDE and HCB to 30.8% for ß-HCH. The highest median concentration was for lindane (380.0 pg/g placenta), followed by p,p'-DDE (280.0 pg/g placenta), and HCB (90.0 pg/g placenta). Exposure to p,p'-DDE was associated with greater meat consumption, suggesting that animal fat is a major source of exposure to DDT metabolites. The frequency of detected PCBs ranged between 70 and 90%; the highest median concentration was for PCB 138 (17.0 pg/g placenta), followed by PCB 153 (16.0 pg/g placenta). All placentas were positive in the estrogenicity bioassay with a median TEXB-α of 0.91 pM Eeq/g of placenta. Exposure to lindane was positively associated with the xenoestrogenicity of TEXB- α, whereas this association was negative in the case of exposure to PCB 153. CONCLUSIONS: To our best knowledge, this study contributes the first evidence on the presence of POPs and xenoestrogenic burden in placentas from Latin-American women. Given concerns about the consequences of prenatal exposure to these compounds on children's health, preventive measures are highly recommended to eliminate or minimize the risk of OCP exposure during pregnancy.

Biodiversity in wetland+ system: a passive solution for HCH dump effluents.

The hexachlorocyclohexane isomers (HCH) are long-banned pesticides. Even though their use has been prohibited for decades, their presence in the environment is still reported worldwide. Wetland + is a registered trademark of the remedial treatment technology consisting of an aerobic sedimentary tank, a permeable reactive barrier, a biosorption system, and an aerobic wetland. This proven method combines a reductive treatment known from PRBs with the natural wetland self-cleaning processes. The average efficiency of the system is 96.8% for chlorobenzenes (ClB) and 81.7% for HCH, during the first 12 months of the system operation. The presence of the genes encoding enzymes involved in the degradation of the HCH compounds indicates that the removal of HCH and ClB occurs not only by chemical removal but also through aerobic and anaerobic combining biodegradation. Changes in abundance and the composition of the diatom community were found to be suitable indicators of the water quality and of the impact of the Wetland + operation on the water ecosystem. The system's annual operation exhibited a markedly higher number of diatom species in the closing profiles of the Ostrovský Creek, the Wetland + effluent recipient.

Targets for pollutants in rat and human pancreatic beta-cells: The effect of prolonged exposure to sub-lethal concentrations of hexachlorocyclohexane isomers on the expression of function- and survival-related proteins.

Decades after most countries banned hexachlorocyclohexane, HCH isomers still pollute the environment. Many studies described HCH as a pro-diabetic factor; nevertheless, the effect of HCH isomers on pancreatic beta-cells remains unexplored. This study investigated the effects of a one-month exposure to α-HCH, ß-HCH, and γ-HCH on protein expression in human (NES2Y) and rat (INS1E) pancreatic beta-cell lines. α-HCH and γ-HCH increased proinsulin and insulin levels in INS1E cells, while ß-HCH showed the opposite trend. α-HCH altered the expression of PKA, ATF3, and PLIN2. ß-HCH affected the expression of GLUT1, GLUT2, PKA, ATF3, p-eIF2α, ATP-CL, and PLIN2. γ-HCH altered the expression of PKA, ATF3, PLIN2, PLIN5, and IDH1. From the tested proteins, PKA, ATF3, and PLIN-2 were the most sensitive to HCH exposure and have the potential to be used as biomarkers.

Degradation of DDT by γ-hexachlorocyclohexane dehydrochlorinase LinA.

1,1,1-Trichloro-2,2-bis(4-chlorophenyl)-ethane (DDT) is the first synthetic insecticide and one of the most widely used pesticides. The use of DDT has been banned, but it remains one of the most notorious environmental pollutants around the world. In this study, we found that γ-hexachlorocyclohexane (γ-HCH) dehydrochlorinase LinA from a γ-HCH-degrading bacterium, Sphingobium japonicum UT26, converts DDT to 1,1-dichloro-2,2-bis(4-chlorophenyl)-ethylene (DDE). Because of the weak DDT degradation activity of LinA, we could not detect such activity in UT26 cells expressing LinA constitutively. However, the linA-deletion mutant of UT26 harboring a plasmid for the expression of LinA, in which LinA was expressed at a higher level than UT26, showed the DDT degradation activity. This outcome highlights the potential for constructing DDT-degrading sphingomonad cells through elevated LinA expression.

Deciphering the kinetics and pathway of lindane biodegradation by novel soil ascomycete fungi for its implication in bioremediation.

Lindane, an organochlorine pesticide, negatively affects living beings and the ecosystem. In this study, the potential of 9 Ascomycetes fungi, isolated from an hexachlorocyclohexane dumpsite soil, was tested for biodegradation of lindane. The strain Pleurostoma richardsiae (FN5) showed lindane biodegradation rate constant (K value) of 0.144 d-1 and a half-life of 4.8d. The formation of intermediate metabolites upon lindane degradation including γ-pentachlorocyclohexene, 2,4-dichlorophenol, phenol, benzene, 1,3- cyclohexadiene, and benzoic acid detected by GC-MS and the potential pathway adopted by the novel fungal strain FN5 for lindane biodegradation has been elucidated. The study of gene profiles with reference to linA and linB in strain FN5 confirmed the same protein family with the reported heterologs from other fungal strains in the NCBI database. This study for the first time provides a thorough understanding of lindane biodegradation by a novel soil-borne Ascomycota fungal strain for its possible application in field-scale bioremediation.

Revelation of bioremediation approaches for hexachlorocyclohexane degradation in soil.

This review elucidates different bioremediation approaches used for degradation of HCH from contaminated sites. It highlights the significance of degradative pathways, microbial diversity and impact of different environmental factors for developing viable bioremediation strategies. The application of innovative biotechnological approaches and a thorough understanding of HCH biodegradation pathways show great promise for the creation of long-term solutions to HCH pollution and the restoration of polluted soil ecosystems. Bioremediation technologies viz. biostimulation, bioaugmentation, phytoremediation have been considered till date for treating HCH-contaminated sites. Different bacterial and fungal strains have been reported for degradation of HCH residues. However, these methods are limited to γ-HCH degradation, at laboratory scale and achieving lower success rate for large scale demonstration trials. This review presents a theoretical background for degradation of different HCH isomers in soil through plants, microbes and through their cooperative interactions. This work briefly overviews the substantial contamination of the environment by HCH residues, along with spontaneous evolution of degradation pathways through various HCH degrading microbes. Bioremediation mechanism and pathways of HCH degradation through plants and microbes have been discussed thoroughly. Through molecular and genetic investigations, the complex metabolic pathways used by these microbes, including reductive dechlorination, hydrolysis, and ring cleavage, has been clarified. This study seeks to give a thorough summary of recent discoveries and developments in bioremediation methods for soil HCH degradation. Numerous microbial consortia, including fungi, plants, and bacteria have been recognised as important participants in the transformation of HCH.

Responses of Anabaena sp. PCC7120 to lindane: Physiological effects and differential expression of potential lin genes.

Lindane (γ-HCH) is an organochlorine pesticide that causes huge environmental concerns worldwide due to its recalcitrance and toxicity. The use of the cyanobacterium Anabaena sp. PCC 7120 in aquatic lindane bioremediation has been suggested but information relative to this process is scarce. In the present work, data relative to the growth, pigment composition, photosynthetic/respiration rate, and oxidative stress response of Anabaena sp. PCC 7120 in the presence of lindane at its solubility limit in water are shown. In addition, lindane degradation experiments revealed almost a total disappearance of lindane in the supernatants of Anabaena sp. PCC 7120 culture after 6 days of incubation. The diminishing in lindane concentration was in concordance with an increase in the levels of trichlorobenzene inside the cells. Furthermore, to identify potential orthologs of the linA, linB, linC, linD, linE, and linR genes from Sphingomonas paucimobilis B90A in Anabaena sp. PCC 7120, a whole genome screening was performed allowing the identification of five putative lin orthologs (all1353 and all0193 putative orthologs of linB, all3836 putative orthologs of linC, and all0352 and alr0353 putative orthologs of linE and linR, respectively) which could be involved in the lindane degradation pathway. Differential expression analysis of these genes in the presence of lindane revealed strong upregulation of one of the potential lin genes of Anabaena sp. PCC 7120.

Enhanced phytotoxicity of 4-chloro-3-methyphenol and lindane under sodium and potassium salt stresses.

Investigating the uptake of organic pollutants by plants under salt stress is critical for evaluating crop contamination, understanding the mechanism of plant uptake, and implementing phytoremediation. The uptake of a highly phytotoxic contaminant, 4-Chloro-3-Methyphenol (CMP, 45 mg L-1), from solutions by wheat seedling with or without Na+ and K+ was studied to illustrate the synergistic effect of salt on phytotoxicity of CMP, using uptake kinetics, transpiration, Ca2+ leakage and fatty acid saturation as indicators. The influence of Na+ and K+ on the uptake of lindane, a relatively low toxic contaminant, from soil was also explored. Under CMP-Na+ and CMP-K+ exposure, the concentrations of CMP in both root and shoot were lower than those under CMP exposure, as a result of the inhibition of transpiration caused by Na+ and K+ stresses. Low concentration of CMP did not reveal serious toxicity on cell membrane. No apparent difference of MDA generation in root cells was observed, due to the lethal concentration of CMP. The relatively small variation of Ca2+ leakage and fatty acid saturation degree in the root cell under exposure of CMP, CMP-Na+ and CMP-K+, compared to intracellular CMP content, suggested the enhanced phytotoxicity of CMP induced by salt. Higher MDA concentration in shoot cell under CMP-Na+ and CMP-K+ exposure compared with that under CMP exposure again showed the synergetic toxicity of CMP. High Na+ and K+ concentration significantly facilitated the uptake of lindane by wheat seedlings in soils, indicating that it could boost the permeability of cell membrane, thereby increasing the toxicity of linande to wheat seedlings. The short-term effect of low salt concentration on the uptake of lindane was not obvious, but long-term exposure also led to increased uptake. In conclusion, the presence of salt could amplify the phtotoxicity of organic contaminant via several mechanisms.

Mycelial nutrient transfer promotes bacterial co-metabolic organochlorine pesticide degradation in nutrient-deprived environments.

Biotransformation of soil organochlorine pesticides (OCP) is often impeded by a lack of nutrients relevant for bacterial growth and/or co-metabolic OCP biotransformation. By providing space-filling mycelia, fungi promote contaminant biodegradation by facilitating bacterial dispersal and the mobilization and release of nutrients in the mycosphere. We here tested whether mycelial nutrient transfer from nutrient-rich to nutrient-deprived areas facilitates bacterial OCP degradation in a nutrient-deficient habitat. The legacy pesticide hexachlorocyclohexane (HCH), a non-HCH-degrading fungus (Fusarium equiseti K3), and a co-metabolically HCH-degrading bacterium (Sphingobium sp. S8) isolated from the same HCH-contaminated soil were used in spatially structured model ecosystems. Using 13C-labeled fungal biomass and protein-based stable isotope probing (protein-SIP), we traced the incorporation of 13C fungal metabolites into bacterial proteins while simultaneously determining the biotransformation of the HCH isomers. The relative isotope abundance (RIA, 7.1-14.2%), labeling ratio (LR, 0.13-0.35), and the shape of isotopic mass distribution profiles of bacterial peptides indicated the transfer of 13C-labeled fungal metabolites into bacterial proteins. Distinct 13C incorporation into the haloalkane dehalogenase (linB) and 2,5-dichloro-2,5-cyclohexadiene-1,4-diol dehydrogenase (LinC), as key enzymes in metabolic HCH degradation, underpin the role of mycelial nutrient transport and fungal-bacterial interactions for co-metabolic bacterial HCH degradation in heterogeneous habitats. Nutrient uptake from mycelia increased HCH removal by twofold as compared to bacterial monocultures. Fungal-bacterial interactions hence may play an important role in the co-metabolic biotransformation of OCP or recalcitrant micropollutants (MPs).

Removal of lindane in liquid culture using soil bacteria and toxicity assessment in human skin fibroblast and HCT116 cell lines.

The development of effective measures for the remediation of lindane contaminated sites is the need of the hour. In this study, a potent lindane degrading bacteria, identified as Rhodococcus rhodochrous NITDBS9 was isolated from an agricultural field of Odisha that could utilize up to 87% of 100 mg L-1 lindane when grown under liquid culture conditions in mineral salt media in 10 days. The bacteria could produce biofilm in lindane-containing media. Rhodococcus rhodochrous NITDBS9 was further characterized for its plant growth-promoting properties and it was found that the bacteria showed abilities for phytohormone, ammonia and biosurfactant production, etc. This could be beneficial for the bioremediation and improvement of crop production in contaminated sites. Ecotoxicity studies carried out for lindane, and its degradation products in mung bean and mustard seeds showed a reduction in toxicity of lindane after treatment with NITDBS9. NITDBS9 was used with a previously isolated potent lindane degrading strain Paracoccus sp. NITDBR1 in a dual mixed culture for the enhanced removal of lindane in the liquid system i.e. up to 93% in 10 days. Cytotoxicity studies were conducted with lindane before and after treatment with the single and dual mixed cultures on human skin fibroblast and HCT116 cell lines. They revealed a significant reduction in toxicity of lindane after it was bioremediated with the single and dual mixed cultures. Therefore, our proposed strategy could be efficiently used for the detoxification of the lindane-contaminated system, and further work should be done to study the use of these cultures in the contaminated soil system.

Degradation effectiveness of hexachlorohexane (ϒ-HCH) by bacterial isolate Bacillus cereus SJPS-2, its gene annotation for bioremediation and comparison with Pseudomonas putida KT2440.

The contamination of Hexachlorohexane (Lindane) in soil and water has toxic effects due to its persistent nature. In our study, an indigenous HCH (gamma isomer) degrading bacterium viz Bacillus cereus SJPS-2 was isolated from Yamuna river water using enrichment culture method. The growth curve indicated that Bacillus cereus SJPS-2 was able to degrade ϒ-HCH effectively with 80.98% degradation. Further, process was improved by using immobilization using alginate beads which showed enhanced degradation (89.34%). Interestingly, in presence of fructose, the ϒ-HCH degradation was up to 79.24% with exponential growth curve whereas the degradation was only 5.61% in presence of glucose revealing diauxic growth curve. Furthermore, The FTIR results confirmed the potential lindane degradation capability of Bacillus cereus SJPS-2 and the bonds were recorded at wavelengths viz. 2900-2500 cm-1, 3300-2800 cm-1 and 785-540 cm-1. Similarity, the GC studies also reconfirmed the degradation potential with retention time (RT) of ethyl acetate and lindane was 2.12 and 11.0 respectively. Further, we studied the metabolic pathway involved for lindane utilization in Bacillus cereus using KEGG-KASS and functional gene annotation through Rapid Annotation using Subsystems Technology (RAST) resulted in the annotation of the lin genes (lin A, lin B, lin C, lin X, lin D, lin E) and respective encoding enzymes. The comparative ϒ-HCH degradation potential of B. cereus and P. putida KT2440 was also evaluated. The island viewer showed the different colors on circular genome indicate the coordinates of genomic islands resulted with some common genomic islands (GEIs) between both bacteria indicating the possibility of horizontal gene transfer at contaminated site or natural environment. These genomic islands (GEIs) contribute in the rearrangement genetic material or to evolve bacteria in stress conditions, as a result the metabolic pathways evolve by formation of catabolic genes. This study establishes the potential of Bacillus cereus SJPS-2 for effectual ϒ-HCH degradation.

Diversity-triggered bottom-up trophic interactions impair key soil functions under lindane pollution stress.

A growing amount of evidence suggests that microbial diversity loss may have negative effects on soil ecosystem function. However, less attention has been paid to the determinants of the relationship between community diversity and soil functioning under pollution stress. Here we manipulated microbial diversity to observe how biotic and abiotic factors influenced soil multi-functions (e.g. lindane degradation, soil respiration and nutrient cycling). Results showed that protist community was more sensitive to dilution, pollution stress, and sodium acetate addition than bacterial and fungal community. Acetate addition accelerated the lindane removal. Any declines in microbial diversity reduced the specialized soil processes (NO3-N production, and N2O flux), but increased soil respiration rate. Dilution led to a significant increase in consumers-bacterial and fungi-bacterial interaction as evidenced by co-occurrence network, which possibly played roles in maintaining microbiome stability and resilience. Interestingly, pollution stress and resource availability weaken the relationship between microbial diversity and soil functions through the bottom-up trophic interaction and environmental preference of soil microbiome. Overall, this work provides experimental evidence that loss in microbial diversity, accompanied with changes in trophic interactions mediated biotic and abiotic factors, could have important consequences for specialized soil functioning in farmland ecosystems.

Chemotactic Bacteria Facilitate the Dispersion of Nonmotile Bacteria through Micrometer-Sized Pores in Engineered Porous Media.

Recent research has demonstrated that chemotactic bacteria can disperse inside microsized pores while traveling toward favorable conditions. Microbe-microbe cotransport might enable nonmotile bacteria to be carried with motile partners to enhance their dispersion and reduce their deposition in porous systems. The aim of this study was to demonstrate the enhancement in the dispersion of nonmotile bacteria (Mycobacterium gilvum VM552, a polycyclic aromatic hydrocarbon-degrader, and Sphingobium sp. D4, a hexachlorocyclohexane-degrader, through micrometer-sized pores near the exclusion-cell-size limit, in the presence of motile Pseudomonas putida G7 cells. For this purpose, we used bioreactors equipped with two chambers that were separated with membrane filters with 3, 5, and 12 µm pore sizes and capillary polydimethylsiloxane (PDMS) microarrays (20 µm × 35 µm × 2.2 mm). The cotransport of nonmotile bacteria occurred exclusively in the presence of a chemoattractant concentration gradient, and therefore, a directed flow of motile cells. This cotransport was more intense in the presence of larger pores (12 µm) and strong chemoeffectors (γ-aminobutyric acid). The mechanism that governed cotransport at the cell scale involved mechanical pushing and hydrodynamic interactions. Chemotaxis-mediated cotransport of bacterial degraders and its implications in pore accessibility opens new avenues for the enhancement of bacterial dispersion in porous media and the biodegradation of heterogeneously contaminated scenarios.

Muscarinic acetylcholine receptor activation synergizes the knockdown and toxicity of GABA-gated chloride channel insecticides.

BACKGROUND: Pest management requires continual identification of new physiological targets and strategies to control pests affecting agriculture and public/animal health. We propose the muscarinic system as a target for agrochemicals because of its physiological importance. Unlike the muscarinic system, gamma-amino butyric acid (GABA) receptors are an established insecticide target. Here, we investigated target-site synergism using small molecule probes (agonist and antagonist) against the muscarinic system and their ability to enhance the toxicity of GABAergic insecticides in Drosophila melanogaster (Meigen). RESULTS: Oral delivery of pilocarpine (muscarinic agonist) enhanced the toxicity of dieldrin, fipronil, and lindane, resulting in synergist ratios (SRs) between 4-32-fold (orally delivered) or between 2-67-fold when insecticides were topically applied. The synergism between pilocarpine and the GABA-insecticides was greater than the synergism observed with atropine (muscarinic antagonist), and was greater, or comparable, to the synergism observed with the metabolic inhibitor piperonyl butoxide. In addition to lethality, pilocarpine increased the knockdown of lindane. The mechanism of synergism was also investigated in the central nervous system using extracellular electrophysiology, where pilocarpine (3 µmo/L) lowered the half-maximal inhibitory concentration (IC50 ) of lindane from 1.3 (0.86-1.98) µmol/L to 0.17 (0.14-0.21) µmol/L and fipronil's IC50 from 2.2 (1.54-3.29) µmol/L to 0.56 (0.40-0.77) µmol/L. CONCLUSION: Convergence of the cellular function between the muscarinic and GABAergic systems enhanced the insecticidal activity of GABA receptor blocking insecticides through the modulation of the central nervous system (CNS). The future impact of the findings could be the reduction of the active ingredient needed in a formulation with the development of muscarinic synergists. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Biodegradation of technical hexachlorocyclohexane by Cupriavidus malaysiensis.

Lindane (γ-Hexachlorocyclohexane) has been used extensively as a pesticide all over the world. The production of Lindane entails the formation of four major Hexachlorocyclohexane (HCH) isomers, that is, alpha, beta, gamma, and delta as muck. These have been used as Technical HCH in developing countries as an inexpensive alternate source. However, HCH isomers pose a severe environmental hazard due to their highly persistent nature and toxicity. In this study, the effect of HCH application on the soil microbial diversity was studied. The species which could persist even after prolonged exposure at high HCH concentration, was isolated, screened, and enriched as potential t-HCH degraders. The selected isolate could degrade 88.05%, 92.19%, 91.54%, and 82.85% of the alpha, gamma, beta, and delta isomers, respectively at 100 mg/L HCH concentration. Identification of the isolate by 16s rRNA sequencing was similar to Cupriavidus malaysiensis. To the best of the authors' knowledge, this is the first study to observe this particular strain's ability to simultaneously degrade the four isomers, especially the most recalcitrant beta isomer. Therefore, the degradative capability of this strain, as a sole carbon source at higher HCH concentration (100 mg/l), can be exploited for bioremediation of HCH contaminated sites.

Stable Carbon Isotope Analysis of Hexachlorocyclohexanes by Liquid-Liquid Extraction Gas Chromatography Isotope Ratio Mass Spectrometry: Method Evaluation and Applications.

Compound specific isotope analysis (CSIA) and enantiomer specific isotope analysis (ESIA) are powerful tools for assessing the fate of hexachlorocyclohexanes (HCHs) in the environment. However, there is no systematic study on the CSIA and ESIA analysis test methods of the carbon isotopes of HCHs in water and soil environments, in particular the isotope fractionation in the pre-concentration process. We endeavored to test the compatibility of CSIA and ESIA with the liquid-liquid extraction method of HCHs in water. The results showed that there were negligible changes in the δ13C of HCHs after extraction, indicating that liquid-liquid extraction can be used as a pre-concentration method for the determination of δ13C of HCHs in water. The optimized method was validated and then applied to differentiate three HCHs from different manufacturers, to identify in situ degradation of HCHs of groundwater from a contaminated site and to resolve the carbon isotope fractionation occurring in the α-HCH oxidation by CaO2/Fe(II) Fenton system. The results showed that the same reagents from different manufacturers have different carbon isotope compositions, and different isomers from the same manufacturer also have different isotope compositions, showing useful evidence in identifying the source of HCHs. The more enriched δ13C in the down-gradient wells indicated that HCHs have undergone biodegradation or/and chemical reactions in the groundwater system of the site. Carbon isotopic enrichment factors (εC) of -1.90 ± 0.10‱ were obtained in the oxidation process. Hence, the method validated in this study has great potential as a method for identifying the degradation of HCHs in a water environment.

Genome evolution related to γ-hexachlorocyclohexane metabolic function in the soil microbial population.

γ-Hexachlorocyclohexane (γ-HCH)-degrading strain, Sphingobium sp. TA15, was newly isolated from an experimental field soil from which the archetypal γ-HCH-degrading strain, S. japonicum UT26, was isolated previously. Comparison of the complete genome sequences of these 2 strains revealed that TA15 shares the same basic genome backbone with UT26, but also has the variable regions that are presumed to have changed either from UT26 or from a putative common ancestor. Organization and localization of lin genes of TA15 were different from those of UT26. It was inferred that transposition of IS6100 had played a crucial role in these genome rearrangements. The accumulation of toxic dead-end products in TA15 was lower than in UT26, suggesting that TA15 utilizes γ-HCH more effectively than UT26. These results suggested that genome evolution related to the γ-HCH metabolic function in the soil microbial population is ongoing.

Grape seed alleviates lindane-induced oxidative stress and improves growth performance, caecal fermentation and antioxidant capacity in growing rabbits.

This study evaluated the protective effect of grape seed on performance, caecal characteristics, blood metabolites and liver antioxidant status in lindane-treated rabbits. Four-week-old New Zealand White rabbits (n = 96) with an initial body weight of 0.750 ± 0.23 g were randomly divided into four groups (n = 24). One group was the control received only corn oil orally, while group L were received lindane daily via gavage in corn oil (4 mg/kg BW; 1/50 LD50 for oral dose), group GS was treated with 50 g grape seed /kg diet, and group LGS treated with a combination of both L and GS for 98 days. Results revealed that final body weight (FBW), average daily gain (ADG), dry matter intake and feed efficiency (FE) were similar between GS and control groups, and achieved the highest FBW and ADG, and the best FE. Caecum pH of the L group increased, while the caecum pH of the GS group decreased sharply. There was a significant increase in the concentration of total VFA, acetic acid, propionic acid and NH3 -N in the GS group, but butyric acid level decreased. GS treatment resulted in a significant increase in the concentrations of total protein, albumin and AChE. GPx, GST, CAT and SOD activity decreased, but TBARS activity significantly increased in the group L, while GS caused a significant elevation of antioxidant activity in the liver. These results confirm that the antioxidant compounds present in grape seed can alleviate the oxidative stress caused by lindane-induced hepatotoxicity and could be a useful supplement to maintain health and improve performance in rabbits.

Lindane removal in contaminated soil by defined microbial consortia and evaluation of its effectiveness by bioassays and cytotoxicity studies.

Lindane contamination in different environmental matrices has been a global concern for long. Bacterial consortia consisting of Paracoccus sp. NITDBR1, Rhodococcus rhodochrous NITDBS9, Ochrobactrum sp. NITDBR3, NITDBR4 and NITDBR5 were used for the bioremediation of soil artificially contaminated with lindane. The bacteria, Paracoccus sp. NITDBR1 and Rhodococcus rhodochrous NITDBS9, have been selected based on their lindane degrading capacity in liquid culture conditions (~80-90 %). The remaining three bacteria were chosen for their auxiliary properties for plant growth promotion, such as nitrogen fixation, phosphate solubilization, indole-3-acetic acid production and ammonia production under in vitro conditions. In this study, market wastes, mainly vegetable wastes, were added to the soil as a biostimulant to form a biomixture for assisting the degradation of lindane by bioaugmentation. Residual lindane was measured at regular intervals of 7 days to monitor the biodegradation process. It was observed that the consortium could degrade ~80% of 50 mg kg-1 lindane in soil which was further increased in the biomixture after six weeks of incubation. Bioassays performed on plant seeds and cytotoxicity studies performed on human skin fibroblast and HCT116 cell lines revealed that the groups contaminated with lindane and treated with the bacterial consortium showed lower toxicity than their respective controls without any bacteria. Hence, the use of both pesticide degrading and plant growth-promoting bacteria in a consortium can be a promising strategy for improved bioremediation against chemical pesticides, particularly in soil and agricultural fields, simultaneously enhancing crop productivity in those contaminated soil.