Decomposition of DDT and its analogs by soil microflora.

A search was made for active cultures that break down DDT. More than 600 microorganisms were isolated from soils treated for a long time with DDT and from accumulating cultures with DDT or its analogs as the carbon source and with DDT or its analogs and supplementary carbon sources. Cultures capable of degrading DDT under conditions of cometabolism were found among them. It was shown that the dechlorination of the trichloromethyl group of DDT was accomplished by a large number of microorganisms and occurred primarily under conditions of limited aeration. The elimination of chloride ions from the aromatic rings occurred only in the presence of cosubstrates under aerobic conditions and only with two strains. The strain Nocardia sp. 306x carried out complete degradation of DDT with the formation of DBH, DCBP, and an as yet unidentified entirely dechlorinated product. The most profound decomposition of DDT was produced by a culture of Ps. aeruginosa 640x, which entirely degraded the DDT molecule with the formation of phenylacetic acid.