Relationship between enantioselective transformation of racemic quizalofop-ethyl and soil bacterial diversity: A destructive approach

This study investigated the resilience of bacterial diversity in soils restored after autoclaving, in terms of richness, evenness and community structure, and its feedback on the enantioselective transformation of racemic quizalofop-ethyl (rac-QE). Microbial biomass carbon (MBC) and bacterial richness (indexed by operational taxonomic units [OTUs]) in restored soil recovered to approximately 50% and 29%, respectively, of the native soil within 43 days. Bacterial evenness was much lower in restored soil than in native soil. The relative proportions of dominant bacterial genera differed significantly (P < .05) between restored and native soils. Importantly, two major bacterial genera that recolonized restored soil were not detected in native soil. Highly enantioselective transformation of rac-QE was observed in restored soils, whereas QE enantiomers exhibited comparable transformation rates in native soils. The second-round enantioselective transformation of rac-QE was altered by the first-round transformation of enantiopure quizalofop-P-ethyl (R-P-QE) in restored and native soils through selective effects of R-P-QE on the bacterial community. The transformation rate of rac-QE was predominantly determined by bacterial abundance and richness, while the enantioselectivity was correlated more with bacterial structure.