CONVERSION OF CHLORINATED PROPANES BY METHYLOSINUS-TRICHOSPORIUM OB3BEXPRESSING SOLUBLE METHANE MONOOXYGENASE

Chlorinated propanes are important pollutants that may show persistent behaviour in the environment. The biotransformation of 1-chloropropan e, 1,2-dichloropropane, 1,3-dichloropropane and 1,2,3-trichloropropane was studied using resting cell suspensions of Methylosinus trichospor ium OB3b expressing soluble methane monooxygenase. The transformation followed first-order kinetics. The rate constants were in the order 1- chloropropane > 1,3-dichloropropane > 1,2-dichloropropane > 1,2,3-tric hloropropane, and varied from 0.07 to 1.03 mi min(-1) mg of cells(-1) for 1,2,3-trichloropropane and 1-chloropropane respectively. Turnover- dependent inactivation occurred for all of the chloropropanes tested. The inactivation constants were lower for 1-chloropropane and 1,2-dich loropropane than for 1,2,3-trichloropropane and 1,3-dichloropropane. N ot all the chloride was released during cometabolic transformation of the chlorinated propanes and production of monochlorinated- and dichlo rinated propanols was found by gas chromatography. The reaction pathwa y of 1,2,3-trichloropropane conversion was studied by mass spectrometr ic analysis of products formed in (H2O)-H-2, which indicated that 1,2, 3-trichloropropane was initially oxidized to 2,3-dichloropropionaldehy de and 1,3-dichloroacetone, depending on whether oxygen insertion occu rred on the C-3 or C-2 carbon of 1,2,3,-trichloropropane, followed by reduction to the corresponding propanols. The results show that chloro propanes are susceptible to cometabolic oxidation by methanotrophs, bu t that the transformation kinetics is worse than with cometabolic conv ersion of trichloroethylene.