Analysis of Substrate Range of Biphenyl-catabolic Enzymes

By using transposon mutants it was demonstrated that biphenyl catabolic Bph enzymes have very relaxed substrate specificities for a variety of aromatic compounds. However, the substrate ranges of the Bph enzymes of two strains used were different from each other. Pseudomonas pseudoalcaligenes KF707 Bph enzymes converted biphenyls substituted with halogen, hydroxyl, methyl, and nitro groups, and biphenylrelated compounds such as biphenylmethane, dibenzyl, diphenylether, diphenylamine, and benzalacetophenone. The same enzyme system was almost inactive for benzene derivatives. Pseudomonas sp. KF712 Bph enzymes showed much broader substrate specificities than those of KF707, since the bphC mutant of this strain converted many benzene derivatives as well as various biphenyls and related compounds to the corresponding dihydroxy compounds.