How microbial consortium-based compound enzyme influences conjugative transfer pathway of antibiotic resistance genes?

Microbial consortium-based compound enzyme (MCE) has been proved to be able to effectively reduce the risk of antibiotic resistance genes (ARGs) dissemination during biotransformation of food waste. However, in-depth mechanisms regarding the regulation of ARGs transfer among environmental bacteria by MCE pretreatment is remain unclear. This work analyzed the effect of MCE pretreatment on RP4 plasmid-mediated conjugative transfer of ARGs and relevant underlying mechanisms. Results showed that MCE pretreatment reduced the plasmid conjugative transfer frequency by 71 % compared with the control. Meanwhile, the reduction of hydrophilic components of extracellular polymeric substances, the decrease of biofilm formation, and the disruption of intercellular contact also happened during MCE pretreatment process. In addition, ATP synthesis and bacterial motility had an effect on the plasmid replication and formation of conjugative transfer channel. These changes lead to down-regulation of the expression of conjugative transfer gene. The inhibitory effect of MCE pretreatment on plasmid conjugative transfer was confirmed in the constructed food waste model. MCE pretreatment reduced the number of pathogens, such as Escherichia-Shigella and Rothia, thereby reduced the potential risk of ARGs being disseminated among pathogens. Overall, this study reveals the key mechanism of MCE pretreatment on disrupting ARGs conjugative transfer, which may provide a crucial theoretical foundation for developing novel interventions to disrupt the environmental dissemination of ARGs in future.