Enantioselective Metabolism of Chiral Fungicide Prothioconazole by <i>Mycobacterium</i> sp. Y-3 and Its Bioaugmentation

Prothioconazole (PTC) is a kind of chiral triazole fungicide widely used in agricultural production, which can easily cause residual contamination and chiral selective toxicity. Microorganisms are the main participants involved in pollutant degradation in the environment. However, studies on the microbial enantioselective degradation of PTC and bioaugmentation of PTC-contaminated soil are still scarce. Herein, we isolated an efficient PTC-degrading strain, <i>Mycobacterium</i> sp. Y-3. Strain Y-3 preferentially metabolized (<i>R</i>)-PTC over (<i>S</i>)-PTC; the degradation rate of (<i>R</i>)-PTC was 2.5 times that of (<i>S</i>)-PTC. The <i>T</i>_1/2 values of 20-80 μM (<i>Rac</i>)-/(<i>S</i>)-/(<i>R</i>)-PTC after treatment with strain Y-3 were 4.1-7.1 h at 37 °C and pH 5.0. The addition of glutamine could significantly enhance the PTC degradation ability of strain Y-3. Strain Y-3 metabolized PTC via methylation to form prothioconazole-<i>S</i>-methyl, the detoxification pathway for PTC. In bioaugmentation experiments, strain Y-3 eliminated PTC residues in the soil within 12 days. High-throughput sequencing analysis indicated that strain Y-3 colonized well in the soil. Inoculation with strain Y-3 reduced soil microbial community diversity and richness, while the bioaugmentation treatment enhanced the soil microbial community associations. These findings provide new insights into the enantioselective microbial metabolism of chiral PTC and <i>in situ</i> bioaugmentation of PTC-contaminated soils.