Copyright © 1997, American Society for Microbiology Methane and Trichloroethylene Oxidation by an Estuarine

An estuarine methanotroph was isolated from sediment enrichments and designated Methylobacter sp. strain BB5.1. In cells grown on medium with added copper, oxidation of methane and trichloroethylene occurred with similar Ks values, but the Vmax for trichloroethylene oxidation was only 0.1 % of the methane oxidation Vmax. Cells grown on low-copper medium did not oxidize trichloroethylene and showed a variable rate of methane oxidation. Methanotrophic bacteria are of interest for bioremediation of sites contaminated with trichloroethylene (TCE) (8, 14) because they are able to oxidize TCE by the methane oxidation system, involving methane monooxygenase (MMO). Two types of MMO are known, a membrane-bound copper-containing form, called the particulate MMO (pMMO), and a cytoplasmic iron-containing form, called the soluble MMO (sMMO) (8, 14, 15, 18, 21). All known methanotrophs contain the pMMO, while only a few strains, mainly Methylosinus and Methylococ-cus species, contain the sMMO as a second enzyme (8). I