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

The rate and products of trichloroethylene (TCE) oxidation by Methylomicrob ium album BG8 expressing membrane-associated methane monooxygenase (pMMO) w ere determined using C-14 radiotracer techniques. [C-14]TCE was degraded at a rate of 1.24 nmol (min mg protein)(-1) with the initial production of gl yoxylate and then formate. Radiolabeled CO2 was also found after incubating M. album BG8 for 5 h with [C-14]TCE. Experiments with purified pMMO from M ethylococcus capsulatus Bath showed that TCE could be mineralized to CO2 by pMMO. Oxygen uptake studies verified that M. album BG8 could oxidize glyox ylate and that pMMO was responsible for the oxidation based on acetylene in activation studies. Here we propose a pathway of TCE oxidation by pMMO-expr essing cells in which TCE is first converted to TCE-epoxide. The epoxide th en spontaneously undergoes HCl elimination to form glyoxylate which can be further oxidized by pMMO to formate and CO2. (C) 2000 Federation of Europea n Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.