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

研究表明，甲烷利用菌广泛存在于自然水体和土壤环境中。不同甲烷利用菌的三氯乙烯降解活性存在较大差异。在这些富集培养物中，从三氯乙烯污染的地下水制备的富集培养物显示出最高的三氯乙烯降解活性。在低甲烷分压的培养条件下，三氯乙烯的降解效果较好。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富集培养物表现出较低的三氯乙烯降解活性。通过乙炔对三氯乙烯降解的抑制实验，证实了三氯乙烯降解的主要酶是甲烷单加氧酶。富集培养物对30 mg/L三氯乙烯有较好的降解效果。富集培养物不能降解四氯乙烯和1，1，1-三氯乙烷，但能降解氯仿。富集培养物的三氯乙烯降解活性随着三氯乙烯的反复接触而下降，由于其生长条件苛刻，未能分离到能降解三氯乙烯的甲烷利用菌。甲烷单加氧酶活性检测可溶性（细胞质）部分，但未检测到颗粒（膜）部分。

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.