Characterization of biphenyl catabolic genes of gram-positive polychlorinated biphenyl degrader rhodococcus sp. strain RHA1

Journal Article · Thu Jun 01 04:00:00 EDT 1995 · Applied and Environmental Microbiology

OSTI ID:96611

Masai, Eiji; Hatta, Takashi; Kimbara, Kazuhide ^[1]

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1. Research Development Corporation of Japan, Shinsan (Japan); and others

Rhodococcus sp. strain RHA1 is a gram-positive polychlorinated biphenyl (PCB) degrader which can degrade 10 ppm of PCB-48 (equivalent to Aroclor 1248), including tri-, tetra-, and pentachlorobiphenyls, in a few days. We isolated the 7.6-kb EcoRI-BamHI fragment carrying the biphenyl catabolic genes of RHA1 and determined their nucleotide sequence. On the basis of deduced amino acid sequence homology, we identified six bph genes, bphA1A2A3A4, bphB, and bphC, that are responsible for the initial three steps of biphenyl degradation. The order of bph genes in RHA1 is bphA1A2A3A4-bphC-bphB. This gene order differs from that of other PCB degraders reported previously. The amino acid sequences deduced from the RHA1 bph genes have a higher degree of homology with the tod genes from Pseudomonas putida F1 (49 to 79%) than with the bph genes of Pseudomonas sp. strains KF707 and KKS102 (30-65%). FIn Escherichia coli, bphA gene activity was not observed even when expression vectors were used. The activities of bphB and bphC, however, were confirmed by observing the transformation of biphenyl to a meta-cleavage compound with the aid of benzene dioxygenase activity that complemented the bphA gene activity (S. Irie, S. Djoi, T. Yorifuji, M. Takagi, and K. Yano, J. Bacteriol. 169:5174-5179, 1987). The expected products of the cloned bph genes, except bphA3, were observed in E. coli in an in vitro transcription-translation system. Insertion mutations of bphA1 and bphC of Rhodococcus sp. strain RHA1 were constructed by gene replacement with cloned gene fragments. The bphA1 and bphC insertion mutants lost the ability to grow on biphenyl, demonstrating that the cloned bph genes are essential for biphenyl catabolism in this strain. 31 refs., 5 figs., 2 tabs.

• OSTI ID: 96611
• Journal Information: Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 6 Vol. 61; ISSN AEMIDF; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
55 BIOLOGY AND MEDICINE
BASIC STUDIES
BIODEGRADATION
BIOLOGICAL PATHWAYS
GENES
POLYCHLORINATED BIPHENYLS
RHODOCOCCUS