Distribution and Evolutionary Signatures of a Broad-Spectrum Pesticide-Degrading Carboxylesterase TriS From Strain S113.

Ester-containing pesticides, such as diphenyl ether herbicides, aryloxyphenoxypropionate herbicides, and strobilurin fungicides, are widely applied in agriculture, but their residues pose significant risks to ecosystems. Functional microorganisms can degrade ester-containing pesticides in the natural environment. However, the microbial mechanisms responsible for their degradation in soils remain unclear. A novel hydrolase gene triS from the strain S113 encoded a broadly active carboxylesterase that hydrolyzes a wide range of ester-containing pesticides. TriS exhibited a maximum sequence similarity of 34.92% to proteins in the Swiss-Prot (UniProt) database. Gene redundancy was observed in strain S113, with TriS showing higher catalytic activity than its homologues. The enzyme contains a conserved Ser226-Glu346-His456 catalytic triad, and its substrate-binding pocket can accommodate complex substrates, which contributes to its broad substrate spectrum and enhanced catalytic efficiency. Genomic analyses revealed that triS resides in a conserved locus, whereas related paralogs occupy more variable regions, suggesting potential horizontal dissemination. Bioinformatics-based taxonomic profiling showed widespread occurrence of TriS homologues, mainly in agricultural soils, and also in forests and wetlands, indicating spread beyond pesticide-treated fields. This study elucidated the function and distribution pattern of triS, enhancing our understanding of microbial ester-containing pesticide degradation in the environment.