Microbial Oxidation of Hydrocarbons and Related Compounds by Whole-Cell Suspensions of the Methane-Oxidizing Bacterium H-2

Abstract

Previously, a thermophilic obligate methane-oxidizing bacterium, H-2 (type I), was isolated in our laboratory. H-2 is a new type of methylotroph because of the G+C content of DNA; it uses both the ribulose monophosphate pathway and the serine pathway for carbon assimilation and possesses a new quinone. In addition, we found that resting cell suspensions of H-2 had the ability to oxidize a variety of compounds different from the other methane-oxidizing bacteria as follows. (i) C(1) to C(8)n-alkanes are hydroxylated and further oxidized, yielding mixtures of the corresponding alcohols, aldehydes, acids, and ketones. Liquid alkanes are transformed through a different oxidative pathway from that of gaseous ones. (ii) Both gaseous (C(2) to C(4)) and liquid (C(5), C(6)) n-alkenes are oxidized to their corresponding 1,2-epoxides. (iii) Liquid monochloro and dichloro n-alkanes (C(5), C(6)) are oxidized, yielding their corresponding acids or haloacids. (iv) Diethyl ether is oxidized to acetic acid; no ethanol and acetaldehyde are detected. (v) Cyclic and aromatic compounds are also oxidized. (vi) Secondary alcohols (C(3) to C(10)) are oxidized to their corresponding methyl ketones.