Deethylsimazine : bacterial dechlorination, deamination, and complete degradation

Abstract

Enrichment cultures utilizing deethylsimazine (6-chloro-N-ethyl-l,3,5-triazine-2,4-diamine)as a sole nitrogen source were obtained from soils that had had long exposure to s-triazine herbicides. A bacterium was isolated that utilized deethylsimazine quantitatively as a nitrogen source for growth, but only 1 mol of nitrogen was obtained/mol of deethylsimazine, whereas all six atoms in melamine were utilized. The bacterium, which was identified as a strain of Rhodococcus corallinus, converted deethylsimazine to 1 mol of 6-(ethylamino)-l,3,5-triazine-2,4(1H,3H)-dione, 1 mol of chloride ion, and 1 mol of ammonium ion. 4-Amino6-(ethylamino)-l,3,5-triazin-2(1H)-one was tentatively identified as a transient intermediate in the degradation, which was presumed to be due to a dechlorination followed by a deamination. Growth of R. corallinus together with Pseudomonas sp. strain NRRL B-12228, which utilized 6-(ethylamino)-1,3,5-triazine-2,4(1H,3H)-dione, resulted in complete conversion of deethylsimazine nitrogen to cell material.