Jiang_2021_Appl.Environ.Microbiol__

Strobilurin fungicides are widely used in agricultural production due to their broad-spectrum and fungal mitochondrial inhibitory activities. However, their massive application has detained the growth of eukaryotic algae and increased the collateral damage in freshwater systems, notably the harmful cyanobacterial blooms (HCBs). In this study, a strobilurin fungicide-degrading strain Hyphomicrobium sp. DY-1 was isolated and characterized successfully. Moreover, a novel esterase gene strH responsible for the de-esterification of strobilurin fungicides was cloned, and the enzymatic properties of StrH were studied. For trifloxystrobin, StrH displayed the maximum activity at 50 degreesC and pH 7.0. The catalytic efficiency (k (cat)/K (m)) of StrH for different strobilurin fungicides were 196.32+/-2.30 microM(-1).s(-1) (trifloxystrobin), 4.64+/-0.05 microM(-1).s(-1) (picoxystrobin), 2.94+/-0.02 microM(-1).s(-1) (pyraclostrobin), and (2.41+/-0.19)x10(-2) microM(-1).s(-1) (azoxystrobin). StrH catalyzed the de-esterification of a variety of strobilurin fungicides generating the corresponding parent acid to achieve the detoxification of strobilurin fungicides and relieve strobilurin fungicides growth inhibition on Chlorella This research will provide insight into the microbial remediation of strobilurin fungicides-contaminated environments.IMPORTANCEStrobilurin fungicides have been widely acknowledged as an essential group of pesticides worldwide. So far, their residues and toxic effects on aquatic organisms have been reported in different parts of the world. Microbial degradation could eliminate xenobiotics from the environment. Therefore, the degradation of strobilurin fungicides by microorganisms has also been reported. However, little is known about the involvement of enzyme or gene in strobilurin fungicides degradation. In this study, a novel esterase gene strH responsible for the detoxification of strobilurin fungicides was cloned in the newly isolated strain Hyphomicrobium sp. DY-1. This degradation process detoxifies the strobilurin fungicides and relieves their growth inhibition on Chlorella.