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

Abstract

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.

Soil Bacterial Diversity Is Positively Correlated with Decomposition Rates during Early Phases of Maize Litter Decomposition

“…In order to manipulate soil microbial diversity, a proportion of NS was autoclaved and reinoculated with microbes that were extracted from NS. In line with previous studies [44,65], we introduced significant shifts in the soil bacterial communities by autoclaving.…”

“…To reduce or eliminate microbes, soils are treated with chloroform fumigation [40], autoclaving [41], or gamma radiation [30,42]. The magnitude of the microbial loss differs depending on sterilization methods (e.g., the number of autoclaving cycles) [43] and incubation conditions after sterilization (e.g., the length of the preincubation period) [44]. Many authors used such sterile soils as substrates and inoculated microbial communities with different diversity levels [30,41,42].…”

Microbial Communities Associated with Methylmercury Degradation in Paddy Soils

“…This result could be attributed to a resilience of microbial community over a long incubation time despite initial suppression, as previously reported. 38,39 Thus, we further conducted microbial analysis for the sterilized soil samples at 120 d. Results of qPCR showed the presence of Hg transformation-related genes (dsrA, dsrB, mcrA, pmoA) in the soil (Figure S2a), although their abundances were much lower than those at day 0. Also, we detected diverse microbial taxa in the sterilized soil (Figure S2b), and some of them are key members that are known to carry merA genes (i.e., Alphaproteobacteria, Actinobacteria, Gammaproteobacteria, Betaproteobacteria, and Bacteroidetes).…”

Enantioselective Catabolism of the Two Enantiomers of the Phenoxyalkanoic Acid Herbicide Dichlorprop by Sphingopyxis sp. DBS4

“…For example, over 99% of ( R )- and ( S )-indoxacarb was degraded in nonsterilized acidic soil after 75 days of incubation, while only 5–10% degraded in sterilized acidic soil . The transformation rate of Rac -quizalofop-ethyl was predominantly determined by bacterial abundance and richness, and the enantioselective degradation was correlated with bacterial structures .…”

“…14 The transformation rate of Rac-quizalofop-ethyl was predominantly determined by bacterial abundance and richness, and the enantioselective degradation was correlated with bacterial structures. 15 In situ amended Rac-DCPP in agricultural soil could be effectively mineralized by the indigenous microbial community and multiple α-ketoglutarate (α-KG)-dependent dioxygenase genes were found to be related to the degradation. 7 Moreover, (R)-and (S)-enantiomers could even be interconverted by soil microorganisms.…”