Studies on the enzymatic characteristics of methar monooxygenase and its trichloroethylene degrading activity

研究表明，利用细菌产生的甲烷广泛存在于自然水和土壤环境中。利用浓缩培养法制备的甲烷对三氯乙烯的降解活性存在较大差异。在这些富集菌中，从三氯乙烯污染的地下水中制备的富集菌对三氯乙烯的降解活性最高。在甲烷分压较低的培养条件下，三氯乙烯得到了有效的降解。处理温度对其降解活性有较大影响。在甲醇培养基上培养的浓缩培养物对三氯乙烯的降解活性较低。乙炔抑制实验表明，三氯乙烯降解的主要酶为甲烷单加氧酶。浓缩培养可有效降解30 mg/L的三氯乙烯。浓缩培养物不能降解四氯乙烯和1，1，1-三氯乙烷，但能降解三氯甲烷。浓缩培养物在与三氯乙烯的反复接触过程中降解三氯乙烯的活性下降，但由于其严格的生长条件而未能分离出能降解三氯乙烯的甲烷利用菌。在可溶性(细胞质)组分中检测到甲烷单加氧酶活性，而在颗粒(膜)组分中未检测到甲烷单加氧酶活性。

We have showed that the methane utilizing bacteria widely inhabit the natural water and soil environments. There existed big differences in the trichloroethylene degrading activities of our prepared methane utilizing enrichment cultures. Among these enrichment cultures, the enrichment culture prepared from the ground water polluted with trichloroethylene showed the highest trichloroethylene degrading activity. Effective trichloroethylene degradation was obtained under the cultural condition with low methane partial pressure. Treatment temperature gave much influence on its degrading activity. Enrichment culture cultivated on methanolic medium showed a low trichloroethylene degrading activity. The responsible enzyme for trichloroethylene degradation was proved to be a methane monooxygenase from the inhibition experiments using acetylene. The enrichment culture degraded 30 mg/L of trichloroethylene effectively. The enrichment culture could not degrade tetrachloroethylene and 1,1,1-trichloroethane, but could degrade chloroform. Trichloroethylene degrading activity of the enrichment culture decreased during the repeated contacts with trichloroethylene.Isolation of methane utilizing bacterium which can degrade trichloroethylene was failed owing to its strict growth condition.Methane monooxygenase belonging to the enrichment culture was studied enzymatically. Methane monooxygenase activity was detected in the soluble (cytoplasmic) fraction, but was not detected in particulate (membrane) fraction.