PSEUDOMONAS SP. STRAIN-273, AN AEROBIC ALPHA,OMEGA-DICHLOROALKANE-DEGRADING BACTERIUM

A gram-negative, aerobic bacterium was isolated from soil; this bacter ium grew in 50% (vol/vol) suspensions of 1,10-dichlorodecane (1,10-DCD ) as the sole source of carbon and energy. Phenotypic and small-subuni t ribosomal RNA characterizations identified the organism, designated strain 273, as a member of the genus Pseudomonas. After induction with I,10-DCD, Pseudomonas sp. strain 273 released stoichiometric amounts of chloride from C-5 to C-12 alpha,omega-dichloroalkanes in the presen ce of oxygen. No dehalogenation occurred under anaerobic conditions. T he best substrates for dehalogenation and growth were C-9 to C-12 chlo roalkanes. The isolate also grew with nonhalogenated aliphatic compoun ds, and decane-grown cells dechlorinated 1,10-DCD without a lag phase. In addition, cells grown on decane dechlorinated I,10-DCD in the pres ence of chloramphenicol, indicating that the 1,10-DCD-dechlorinating e nzyme system was also induced by decane. Other known alkane-degrading Pseudomonas species did not grow with 1,10-DCD as a carbon source. Dec hlorination of 1,10-DCD was demonstrated in cell extracts of Pseudomon as sp. strain 273. Cell-free activity was strictly oxygen dependent, a nd NADH stimulated dechlorination, whereas EDTA had an inhibitory effe ct.