溶解性生物炭对铜绿假单胞菌耐药性影响及群体感应的响应机制

Effect of dissolved biochar on the antibiotic resistance of Pseudomonas aeruginosa and response mechanism of quorum sensing

微生物耐药是当前全球最严峻的公共健康问题之一.虽然环境耐药近来得到了广泛关注,但其影响的内在机制仍有待深入.本文以铜绿假单胞菌(Pseudomonas aeruginosa PAO1)为模式菌株,以微生物细胞间“对话”即群体感应为切入点,以玉米秸秆为前体物质裂解制备得到溶解性生物质炭(Dissolved biochar,DBC),探究了环境中广泛存在的DBC对PAO1耐药性影响及群体感应响应机制.结果表明,10~50 mg·L^(-1)的DBC可以不同程度地抑制PAO1生物膜形成和群感信号分子产生,20.0 mg·L^(-1)的DBC可使PAO1生物膜量降低32.1%,并显著抑制OC_(12)-HSL(36.1%)和C_(4)-HSL(45.7%)的产生.亚致死浓度(10.0 mg·L^(-1))DBC对PAO1的长期胁使PAO1生物膜形成呈先抑制后促进的现象,在胁迫60d进化PAO1菌株已经完全适应了DBC的胁迫,生物膜量增加了22.2%,且对阿奇霉素的耐药性增加;C_(4)-HSL产生和群感基因(rhlI、lasI、lasR和rhlR)表达量均显著增加.本文阐明了DBC对耐药微生物耐药性影响及群体感应的响应机制,以期为深入理解真实环境中耐药微生物群体感应调控行为和耐药阻控策略提供重要参考.

Microbial resistance is one of the most concerned public health issues in the world.Although environmental drug resistance has received extensive attention recently,further research is needed to understand the underlying mechanism.In this study,we investigated the impact of dissolved biochar(DBC)derived from the pyrolysis of corn stalk on the drug resistance of Pseudomonas aeruginosa PAO1 and the response mechanism of quorum sensing.The results showed that 10~50 mg·L^(-1)of DBC inhibited the formation of PAO1 biofilm and the production of quorum sensing signal molecules.Specifically,20 mg·L^(-1)of DBC reduced the biomass of PAO1 biofilm by 32.1%,and significantly suppressed the production of OC_(12)-HSL(36.1%)and C_(4)-HSL(45.7%).Long-term exposure of PAO1 to sub-lethal concentration(10 mg·L^(-1))of DBC first inhibited and then promoted the formation of PAO1 biofilm.After a 60-d treatment,the evolved PAO1 strain completely adapted to the stress of DBC,with a 22.2%of increase in biofilm biomass,and enhanced resistance to azithromycin.Additionally,the production of C_(4)-HSL and the expression of quorum sensing genes(rhlI,lasI,lasR and rhlR)also significantly increased.This study provides valuable insights into the influence of DBC on drug-resistant microbial resistance and the response mechanisms of quorum sensing.The findings contribute to an in-depth understanding of the regulatory behavior of drug-resistant microbial quorum sensing and antibiotic resistance control strategy in real environments.