Involvement of a Quinoprotein Alcohol Dehydrogenase and an NAD-dependent Aldehyde Dehydrogenase in 2-Chloroethanol Metabolism in Xanthobacter autotrophicus GJlO

An inducible methanol dehydrogenase showing high activity with 2-chloroethanol was purified from 2-chloroethanol-grown cells of the 1,2-dichloroethane utilizing bacterium Xanthobacter autotrophicus GJ10. The enzyme consisted of a 60 kDa polypeptide that was associated with a 10 kDa polypeptide and contained pyrrolo-quinoline quinone (PQQ) as a prosthetic group. Chloroethanol-grown cells of strain G J 10 also contained an inducible NAD-dependent chloroacetaldehyde dehydrogenase. Its involvement in the metabolism of 2-chloroethanol was inferred from its absence in a 2-chloroethanol non-utilizing mutant. Three different isolates of X . autotrophicus that do not utilize 2-chloroethanol for growth produced chloroethanol dehydrogenase and chloroacetaldehyde dehydrogenase activities at similar levels as strain GJ10. It is concluded that both dehydrogenases are involved in the metabolism of natural compounds and due to their broad substrate specificity fortuitously also play a role in the metabolism of the xenobiotic compounds 1,2-dichloroethane and 2-chloroethanol.