THE ATRAZINE CATABOLISM GENES ATZABC ARE WIDESPREAD AND HIGHLY CONSERVED

Pseudormonas strain ADP metabolizes the herbicide atrazine via three e nzymatic steps, encoded by the genes atzABC, to yield cyanuric acid, a nitrogen source for many bacteria. Here, we show that five geographic ally distinct atrazine-degrading bacteria contain genes homologous to atzA, -B, and -C. The sequence identities of the atz genes from differ ent atrazine-degrading bacteria were greater than 99% in all pairwise comparisons. This differs from bacterial genes involved in the catabol ism of other chlorinated compounds, for which the average sequence ide ntity in pairwise comparisons of the known members of a class ranged f rom 25 to 56%. Our results indicate that globally distributed atrazine -catabolic genes are highly conserved in diverse genera of bacteria.