Biotransformation of phenanthrene and 1-methoxynaphthalene with Streptomyces lividans cells expressing a marine bacterial phenanthrene dioxygenase gene cluster

The phdABCD gene cluster in a marine bacterium Nocardioides sp. strain KP7 codes for the multicomponent enzyme phenanthrene dioxygenase. phdA encoding an iron-sulfur protein large subunit alpha, phdB encoding its small subuni t beta, phdC encoding ferredoxin, and phdD encoding ferredoxin reductase, w ere replaced in such a way that the termination codons of the preceding ope n reading frames were overlapped with the initiation codons of the followin g genes. This manipulated phdABCD gene cluster was positioned downstream of the thiostrepton-inducible promoter PtipA in a high-copy-number vector pIJ 6021, and introduced into the gram-positive, soil-inhabiting, filamentous b acterium Streptomyces lividans. The recombinant,S. lividans cells converted phenanthrene into a cis-diol form, which was determined to be cis-3,4-dihy droxy-3,4-dihydrophenanthrene by its UV spectral data as well as HPLC prope rty, using the authentic sample for comparison. This biotransformation proc eeded very efficiently; 200,um and 2 mar of phenanthrene were almost comple tely converted to its cis-diol form in 6 h and 32 h, respectively. In addit ion, the S. lividans cells carrying the phdABCD gene cluster were found to transform 1-methoxynaphthalene to two products, which were identified to be 8-methoxy-2-naphthol in addition to 8-methoxy-1,2-dihydro-1,2-naphthalened iol by their EI-MS, H-1- and C-13-NMR spectral data.