[Degradation of 3-chlorobenzoic acid by a Pseudomonas putida strain]

A Pseudomonas putida strain 87 capable of assimilating 3-chlorobenzoic acid as a sole source of carbon and energy (3Cba+) was isolated. Treatment with mitomycin C eliminated the 3Cba+ phenotype in 1% of cells in the population. The 3Cba+ phenotype was transferred at a low frequency in the process of conjugation to other bacteria belonging to the genus Pseudomonas. Determinants localized on the plasmid are presumed to be responsible for the capability to assimilate 3-chlorobenzoic acid. A scheme is proposed for the oxidation of 3-chlorobenzoic acid on the basis of studying the products of its degradation. Two catechol 1,2-dioxygenases are present in strains with the 3Cba+ phenotype as was shown by analysing the activity of enzymes catalysing cleavage of the aromatic cycle and by studying their induction. One of the two seems to be encoded by chromosomal genes while the other is encoded by plasmid genes and determines the capability of the culture to cleave the chlorinated pyrocatechol.