Microbial degradation of Ammeline

Abstract

Ammeline is a common product of the degradation of s-triazine herbicides. The biodegradation of ammeline by 165 microbial strains has been investigated. 95% of all strains tested were able to degrade ammeline to ammelide and 35% could degrade ammelide further to cyanuric acid which was accumulated in the growth medium. Only strain CBS 472.48 of Sporothrix schenckii was capable of metabolizing ammeline slowly to carbon dioxide and ammonium. The highest specific rate for ammeline degraded to cyanuric acid was 3.3 μkat × kg dry weight of cells⁻¹. The deamination of ammelide was usually the rate-limiting step. The enzymes degrading ammeline to cyanuric acid were formed constitutively. Ammonium and urea, however, caused repression of enzyme synthesis, and ammonium caused a slight inhibition of the ammeline-degrading enzyme activity. Efficient degradation of ammeline to carbon dioxide and ammonium (0.4 μkat × kg dry weight of cells⁻¹) could be achieved using a mixed culture of a pseudomonad, strain 123 B, and a fungus, Sporothrix schenckii strain 6.2.