Triazophos is a widely used organophosphorous insecticide, and its presence in the environment is increasing. It induces point mutations in the fruit fly, Drosophila melanogaster ([http://www.ncbi.nlm.nih.gov/pubmed/2123939|Velazquez et al., 1990]). Thus its microbial degradation is of interest. Diaphorobacter sp. TPD-1 can grow on triazophos as its sole source of carbon. The initial step in its degradation involves hydrolysis of the P-O ester to form 1-phenyl-3-hydroxy-1,2,4-triazole (PHT) and o,o-diethylphosphorothioate. Next, the triazole ring of PHT is cleaved to form (E)-1-formyl-2-phenyldiazene, with release of CH3NO2 as one or more compounds in one or more steps. The diazene is tranformed to 2-phenylhydrazinecarboxylate in one or two steps. The latter compound is decarboxylated to phenylhydrazine ([http://www.ncbi.nlm.nih.gov/pubmed/21212954|Yang et al., 2011]). The first reaction is well-characterized; there may be other routes to the other products. Klebsiella sp. E6 can grow on triazophos as its sole source of carbon, nitrogen and phosphorous. The first step in its degradation is the same as above. It can completely mineralize triazophos, but its degradation pathway has not been determined ([http://www.ncbi.nlm.nih.gov/pubmed/16243454|Wang et al., 2005]).