新乡学院于涛副教授课题组在细菌LuxS/AI-2群体感应系统对消毒剂的响应机制方面取得新进展

近日，新乡学院生命科学与基础医学学院于涛副教授课题组在细菌LuxS/AI-2群体感应系统对消毒剂的响应机制方面取得新进展，相关成果“The effect of sublethal concentrations of benzalkonium chloride on the LuxS/AI-2 quorum sensing system, biofilm formation and motility of Escherichia coli”以研究论文形式发表于International Journal of Food Microbiology（农林科学1区，IF=5.277）。本研究成果得到了河南省自然科学基金（202300410018）和河南省高等学校重点科研项目（20A180027）的资助。新乡学院为成果第一署名单位，生命科学与基础医学学院陈磊山教授为通讯作者，于涛副教授为第一作者。

LuxS介导的群体感应（Quorum sensing，QS）系统细菌中普遍存在，LuxS酶在多种细菌中高度保守，参与通用信号分子AI-2的生物合成，且LuxS/AI-2系统与细菌的生物被膜形成、鞭毛表达组装以及毒力基因表达等重要表型相关。目前有关消毒剂对细菌QS系统影响的研究还较少，该研究聚焦季铵盐类消毒剂苯扎氯铵（BC）对大肠杆菌（E. coli）LuxS/AI-2系统及其所调控的细菌表型的影响。研究结果表明，在亚致死浓度下，BC能够激活E. coli的LuxS/AI-2系统，使luxS基因表达量升高，AI-2合成量增加，信号分子AI-2则会进一步调控wza、wcaA,和fli等基因的表达，从而促进E. coli生物被膜的形成。因此，消毒剂的不合理使用可能会增加细菌对食品安全和人类健康的潜在威胁。

The effect of sublethal concentrations of benzalkonium chloride on the LuxS/AI-2 quorum sensing system, biofilm formation and motility of Escherichia coli

Tao Yu^ab1, Muyuan Ma^c1, Yaxi Sun^a, Xiaobo Xu^a, Shuxing Qiu^ab, Junlei Yin^ab,Leishan Chen^a

^aSchool of Life Sciences & Basic Medicine, Xinxiang University, Xinxiang, Henan Province 453000, China

^bKey Laboratory of Biomedicine and Health Risk Warning of Xinxiang City, Xinxiang, Henan Province 453000, China

^cDepartment of Biological Sciences, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu Province 215123, China

Abstract

Escherichia coli can survive improper disinfection processes, which is a potential source of contamination of food products. Benzalkonium chloride (BC) is a common disinfectant widely used in food industry. Bacterial quorum sensing (QS) plays a major role in food spoilage, biofilm formation and food-related pathogenesis. Understanding QS can help to control the growth of undesirable food-related bacteria. The LuxS/AI-2 QS system of E. coli has been confirmed to regulate many important phenotypes including biofilm formation and motility. In the current study, we aimed to investigate the effect of sublethal concentrations of BC on the LuxS/AI-2 system of E. coli isolates from retail meat samples, as well as bacterial biofilm formation and motility. Our results showed that sublethal concentrations of BC promoted AI-2 production in four test E. coli isolates. The results from microplate assay and confocal laser scanning microscopy (CLSM) analysis indicated that sublethal concentrations of BC enhanced biofilm formation of E. coli. When treated with sublethal concentrations of BC, exopolysaccharides (EPS) production during biofilm development increased significantly and swimming motility of tested isolates was also promoted. The expression levels of luxS, biofilm-associated genes and flagellar motility genes were increased by BC at sublethal concentrations. Our findings underline the importance of proper use of the disinfectant BC in food processing environments to control food contamination by E. coli.