Characterization and genome functional analysis of the DDT-degrading bacterium Ochrobactrum sp DDT-2

A strain of Ochrobactrum sp. DDT-2 that was capable of degrading DDT as the sole carbon and energy sourcewas isolated and sequenced, and its biodegradation characteristics and metabolismmechanism were examined. The genome sequence of the isolate DDT-2was composed of 4,630,303 bp with a GC content of 55.99% and 4454 coding genes. The degradation rate of DDT by the isolate DDT-2 increased with the increasing substrate concentration (0.1-10 mg/l) and temperature (20-40 degrees C). The degradation half-life of DDT in the presence of the isolate DDT-2 at pH 7.0 was obviously shorter than those at pH 5.0 and 9.0. Potential DDT degradation genes were found in the isolate DDT-2 genome by a BLASTx search against a DDT degradation genes (DDGs) database. A common biodegradation pathway of DDT was proposed based on the combined analysis of genome annotation and mass spectrometry. DDT was initially dechlorinated to form DDD and DDE. Then, it was transformed into DDMU and DDA via dechlorination and carboxylation, and it may ultimately be mineralized to carbon dioxide. The results suggested that the isolate DDT-2 could be useful for the bioremediation of DDT and its metabolite residues. (C) 2017 Elsevier B.V. All rights reserved.