Antimicrobial agents enter the ecological environment through animal excreta and disrupt metabolism in environmental microorganisms. Quorum sensing (QS) can help bacteria adapt to their surroundings. To explore how acyl-homoserine lactone (AHL) can adjust the influence of florfenicol on nitrogen cycling and methane metabolism in anaerobic fermentation, a small indoor thermostatic anaerobic fermentation model was established by adding exogenous acylated homoserine lactone (AHL) signal molecules with florfenicol as the stress factor. Through bacterial function prediction by PICRUST, we found that the addition of AHL further increased the promotion of methanogenesis_by_CO2_reduction_with_H2 and hydrogenotrophic methanogenesis by florfenicol. Before the third sampling, florfenicol significantly inhibited the enrichment of the denitrification pathway microbiota, whereas the addition of AHL significantly promoted the enrichment of the denitrification pathway microbiota. Functional annotation showed that florfenicol exposure stress significantly affected nitrogen and methane metabolism, and the addition of AHLs reduced the response of functional genes to florfenicol. All nitrogen cycling enzymes with significantly different abundances in treatment groups were substantially associated with methane-metabolizing enzymes. Glutamate metabolism is significant in the process of anaerobic fermentation, and is a correlation point between nitrogen and methane metabolism. In our experiment, AHL was the influencing factor at the highest latitude that directly regulates the metabolism of NO3--N and the degradation process of florfenicol. The addition of AHL curbed the inhibitory effect of florfenicol on some functional microbiota, improved the stability of fermentation microbiota, and weakened the impact of antibiotic residues by improving its degradation efficiency.
Keywords: Anaerobic fermentation; Florfenicol; Methane metabolism; Nitrogen cycling; Quorum sensing.
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