THE ATZABC GENES ENCODING ATRAZINE CATABOLISM ARE LOCATED ON A SELF-TRANSMISSIBLE PLASMID IN PSEUDOMONAS SP. STRAIN ADP

Pseudomonas sp. strain ADP initiates atrazine catabolism via three enz ymatic steps, encoded by atzA, -B, and -C, which yield cyanuric acid, a nitrogen source for many bacteria. In-well lysis, Southern hybridiza tion, and plasmid transfer studies indicated that the atzA, -B, and -C genes are localized on a 96-kb self-transmissible plasmid, pADP-1, in Pseudomonas sp. strain ADP. High-performance liquid chromatography an alyses showed that cyanuric acid degradation was not encoded by pADP-1 . pADP-1 was transferred to Escherichia coli strains at a frequency of 4.7 x 10(-2). This suggests a potential molecular mechanism for the d ispersion of the atzABC genes to other soil bacteria.