Department of Food Microbiology, Central Food Technological Research Institute, Mysore 570 013, Karnataka State, India.
J Agric Food Chem. 2010 Jan 27;58(2):1046-54. doi: 10.1021/jf9038259.
Widespread contamination of the environment, globally, has been caused by extensive and indiscriminate use of hexachlorocyclohexane (HCH) as an insecticide since the 1940s, threatening the biota including humans, and there is an urgent need to eliminate it, preferably through bioremediation technologies. A gamma-HCH-degrading microbial consortium was isolated by enrichment of a soil sample from a sugar cane field having a long history of technical grade HCH application. On acclimation the degrading ability improved substantially. The consortium, which took 10 days to degrade 25 microg mL(-1) of gamma-HCH, initially could mineralize even 300 microg mL(-1) of the substrate within 108 h on acclimation. With 300 microg mL(-1) substrate, the rate of degradation, as calculated for the early exponential phase, was 216 microg mL(-1) day(-1), the highest reported so far. An amount of 400 microg mL(-1) of gamma-HCH, however, was mineralized partially with only 78% Cl(-) release. No apparent accumulation of intermediary metabolites was observed up to 300 microg mL(-1) substrate, indicating a fast rate of mineralization. Aeration, mesophilic temperatures (20-35 degrees C), and near neutral pH (6.0-8.0) were favorable conditions for degradation. The presence of glucose at 1000 microg mL(-1) retarded the degradation, whereas cellulose and sawdust at 1600 microg mL(-1) and glucose at 100 microg mL(-1) did not show any marked effect. The consortium also mineralized alpha-, beta-, and delta-HCH efficiently. The consortium consisted of nine bacterial strains and a fungal strain, and individually they were able to degrade 10 microg mL(-1) of gamma-HCH. This mixed culture holds high potential for deployment in bioremediation of HCH-contaminated soils, waste dumpsites, and water bodies.
全球范围内，由于自 20 世纪 40 年代以来广泛且无差别地将六氯环己烷（HCH）用作杀虫剂，环境受到了广泛的污染，这对包括人类在内的生物区系构成了威胁，因此迫切需要通过生物修复技术来消除 HCH。从一个长期使用工业级 HCH 的甘蔗地土壤样本中通过富集的方法分离出了一个能够降解γ-HCH 的微生物混合菌群。在驯化过程中，该菌群的降解能力显著提高。该菌群在驯化 10 天后，能够在 108 小时内将 300μg mL(-1)的底物矿化，而最初只能降解 25μg mL(-1)的γ-HCH。在底物浓度为 300μg mL(-1)时，根据早期指数期计算，降解速度为 216μg mL(-1) day(-1)，这是迄今为止报道的最高值。然而，当底物浓度为 400μg mL(-1)时，只有 78%的 Cl(-)被释放，部分底物被矿化。在 300μg mL(-1)的底物浓度下，没有观察到明显的中间代谢物积累，表明矿化速度很快。通气、中温（20-35℃）和近中性 pH（6.0-8.0）是有利于降解的条件。在 1000μg mL(-1)的葡萄糖存在下，降解会受到抑制，而在 1600μg mL(-1)的纤维素和木屑以及 100μg mL(-1)的葡萄糖存在下，降解没有明显的影响。该混合菌群也能有效地矿化α-、β-和δ-HCH。该混合菌群由 9 株细菌和 1 株真菌组成，它们单独培养时都能降解 10μg mL(-1)的γ-HCH。这种混合培养物在用于生物修复 HCH 污染的土壤、垃圾填埋场和水体方面具有很大的潜力。
