THE LOWER PATHWAY OPERON FOR BENZOATE CATABOLISM IN BIPHENYL-UTILIZING PSEUDOMONAS SP STRAIN-IC AND THE NUCLEOTIDE-SEQUENCE OF THE BPHE GENE FOR CATECHOL 2,3-DIOXYGENASE

Pseudomonas sp. strain IC is able to grow on biphenyl, 3-methylbipheny l and 4-methylbiphenyl. These are converted to benzoate and the corres ponding methylbenzoates. The lower pathway genes for the catabolism of the benzoates were cloned on a 22 kb HindIII fragment. Hybridization with gene-specific probes from the meta pathways of other catabolic pl asmids showed that the gene order was identical to that of the operons carrying the same function from TOL plasmids. The nucleotide sequence of a 1241 bp region carrying the whole of the bphE gene (for a catech ol 2,3-dioxygenase) and the 5' end of the downstream bphG gene (for 2- hydroxy semialdehyde dehydrogenase) was determined. Both genes showed a high degree of homology with genes encoding isofunctional proteins f rom other Pseudomonas strains. The upper pathway genes for the convers ion of biphenyl to benzoate have also been cloned but no linkage with the lower pathway operon has been detected. Pseudomonas strain IC cont ains a large plasmid pWW110 (> 200 kb) and there are indications that this plasmid carries the bph genes.