Unveiling highly efficient degradation mechanism of strobilurin fungicides by strain Hyphomicrobium sp. DY-1

Strobilurin fungicides are a type of agricultural chemical commonly used to control fungal diseases in crops. However, the abuse of strobilurin fungicides leads to heavy residue in the environment, posing serious threats to ecosystems and human health. In this regard, the strains Hyphomicrobium sp. DY-1 and Hyphomicrobium sp. B1 could hydrolyze the strobilurin fungicides effectively (trifloxystrobin, azoxystrobin, pyraclostrobin, and picox-ystrobin), generating the corresponding parent acid. Therefore, the present study sought to explore the molecular degradation mechanism of strobilurin fungicides by strain DY-1. The results showed that strain DY-1 exhibited a faster degradation rate for strobilurin fungicides than strain B1. Comparative genomic analysis and functional verification of both strains revealed that strain DY-1 possesses six strobilurin hydrolases (TriH, StrH, StrH1, StrH2, StrH3, and StrH4), whereas strain B1 possesses only three strobilurin hydrolases (TriH, StrH, and StrH1). All StrHs (StrH1, StrH2, StrH3, and StrH4) shared 50%-77% identity with StrH and contained conserved cata-lytic motif Ser-Glu-His. Further investigation into the distribution of strobilurin fungicide hydrolases revealed that strH and strH1 were aligned together and surrounded by transposases in the strains DY-1 and B1 and a genomic island containing strH and strH1 derived from the Hyphomicrobium genus. Overall, the function, diversity, and distribution of strobilurin hydrolases will provide insights into the microbial degradation of stro-bilurin fungicides.