甲烷利用细菌降解三氯乙烯的研究

GYJ3菌株细胞微细结构的电镜观察结果表明：它具有Ⅱ型甲烷利用细菌的特征，应归属于Ⅱ型菌。考察了Cu2+浓度、培养气相中甲烷浓度对菌株细胞中甲烷单加氧酶（EC1．14．13．25，简称MMO）活性的影响。结果表明，培养液中Cu2+浓度为1．5μmol／L，培养气相中甲烷：空气比为2∶1时，可溶性甲烷单加氧酶占细胞中MMO总量的95％。研究了GYJ3菌株细胞悬浮液降解三氯乙烯过程。实验结果表明，GYJ3菌株能够降解不同浓度的三氯乙烯，较高浓度的三氯乙烯对降解反应没有明最的抑制作用。加入甲酸盐作为电子给体能够提高三氯乙烯降解反应速率。实验中观察到GYJ3菌株降解三氯乙烯过程中反应速率随着反应的进行而下降，在三氯乙烯降解过程中三氯乙烯氧化产物是导致细胞失活的主要原因。实验室中测定了GYJ3菌株单位重量细胞降解三氯乙烯极限量，它可作为评价细菌降解三氯乙烯能力的重要指标。

THE BIODEGRADATION OF TRICHLOROETHYLENE BY A METHANOTROPHIC BACTERIUM

A Methylomonas (strain GYJ3) isolated in our laboratory was identified as the type II methanotroph on the basis of the intractytoplasmic membrane of the ultrastructure. The optimal culture conditions for production of the soluble from of methane monooxygenase (MMO) were determined, in which the ratio of methane to air in atmosphere was 2 to 1 and Cu2+ concentration was 1.5 mumol/L. The biodegradation of trichoroethylene(TCE) by the resting cells of the strain GYJ3 was studied. All experiments were performed with cells grown under above conditions and thus expressing soluble MMO. This results showed that TCE at the high concentration of 30 mg/L did not inhibit to the enzymes in the cells. Addition of formate increased the initial specific TCE degradation rates. The product of TCE oxidation was found to be toxic to the cells. The degree of inactivation of MMO was proportional to the amount of TCE degraded. The TCE degradation capacities(Tc) of resting cells was determined. In no-formate and formate-fed experiments, the TCE degradation capacities were found to be 0.0778 and 0.0851 mg of TCE/mg of dry cell, respectively.