[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.