Identification of intermediates of in vivo trichloroethylene oxidation by the membrane-associated methane monooxygenase

摘要

The rate and products of trichloroethylene (TCE) oxidation by Methylomicrobium album BG8 expressing membrane-associated methane monooxygenase (pMMO) were determined using 14 C radiotracer techniques. [ 14 C]TCE was degraded at a rate of 1.24 nmol (min mg protein) −1 with the initial production of glyoxylate and then formate. Radiolabeled CO 2 was also found after incubating M. album BG8 for 5 h with [ 14 C]TCE. Experiments with purified pMMO from Methylococcus capsulatus Bath showed that TCE could be mineralized to CO 2 by pMMO. Oxygen uptake studies verified that M. album BG8 could oxidize glyoxylate and that pMMO was responsible for the oxidation based on acetylene inactivation studies. Here we propose a pathway of TCE oxidation by pMMO-expressing cells in which TCE is first converted to TCE-epoxide. The epoxide then spontaneously undergoes HCl elimination to form glyoxylate which can be further oxidized by pMMO to formate and CO 2 .