OXIDATIVE DEHALOGENATION OF 2-CHLOROBENZOATE AND 2,4-DICHLOROBENZOATEBY PSEUDOMONAS-AERUGINOSA

Strain Pseudomonas aeruginosa 142 was isolated from a bacterial associ ation which utilized polychlorinated biphenyls. The strain was capable of growing on 2-chloro- and 2,4-dichlorobenzoates as the sole carbon and energy sources and did not utilize 3- and 4-chloro- or 3,5- and 2, 6-dichlorobenzoates. P. aeruginosa 142 dehalogenated 2-chlorobenzoate, 2,4-dichlorobenzoate, and 2,5-dichlorobenzoate under aerobic conditio ns no matter whether it was grown on 2-chlorobenzoate or 2,4-chloroben zoate. Liberation of chlorine was not observed under microaerobic and anaerobic conditions. The activity of catechol-1,2-dioxygenase was fou nd in cell-free extracts, but not of other enzymes of aromatic ring cl eavage. During growth on 2,4-dichlorobenzoate, two catechol-1,2-oxygen ases were found, one of which was catechol-1,2-oxygenase, and the othe r was 4-chlorocatechol-1,2-oxygenase. None of the methods used reveale d plasmids. On the basis of the results obtained it is concluded that the first stage of the metabolism of 2-chloro-, 2,4-, and 2,5-dichloro benzoates is oxidative elimination of chlorine at the ortho-position. Subsequent cleavage of the corresponding catechols occurs via the orth o-pathway.