Isolation and characterisation of Rhodococcus erythropolis TA57 able to degrade the triazine amine product from hydrolysis of sulfonylurea pesticidesin soils

We isolated a bacterium capable of metabolising a methylated and methoxylat ed s-triazine ring as the only nitrogen source. On a weight basis, the s-tr iazine, commonly named triazine amine (TAM), constitutes approx. half of se veral sulfonylurea herbicides and is formed after hydrolysis of these herbi cides. The isolate, strain TA57 was identified using multi-phasic taxonomy as a gram-positive Rhodococcus erythropolis. Strain TA57 mineralised over 5 0% C-14-labelled TAM within 4 days in growing cultures using all of the nit rogen for growth. The degradation capacity was found stable in cells grown on either tryptic soy broth agar plates or in minimal medium with NH4+. Amo ng other s-triazines tested, only one other methylated, but de-methoxylated s-triazine amine supported growth. Inoculating 10(6) cells of TA57 per gra m of soil (d.w.) resulted in 50% mineralisation of C-14-iabelled TAM (1 mg k(-1)) within 25 days, in contrary to the indigenous population that minera lised only 6% in 50 days.