食源性致病菌是食品安全的重要风险隐患，运用食品添加剂是常用的控制手段。含硫香料是一类重要的食用香料，其中硫醚类香料对常见致病菌具有良好的抑菌效果。然而，其他种类的含硫香料的抑菌效果如何？具有强抑菌功效的含硫香料如何消减致病菌的毒力？目前仍未明确。针对上述问题，本项目拟以金黄色葡萄球菌、单增李斯特菌、大肠埃希氏菌O157:H7及鼠伤寒沙门氏菌为供试菌，从毒力因子表达和细胞免疫应答两方面研究含硫香料对致病菌的毒力消减作用的分子机制。首先，全面系统筛选具有高抑菌活性的含硫香料，通过细菌代谢动力学，明确含硫香料毒力消减作用的适宜条件。其次，采用RT-qPCR、Western blotting的方法，研究含硫香料对毒力因子基因和蛋白质表达的影响，明确靶点毒力分子。最后，采用流式细胞仪、基因芯片等分子生物学手段，研究含硫香料对致病菌及靶点毒素引起的细胞免疫应答的影响，为丰富食品防腐因子奠定研究基础。

Foodborne pathogens are critical in food safety risk, and usage of food additive is common control method. Sulfur-containing flavor compounds have become a very important class of flavors, in which sulfides have good antibacterial activities against common pathogens. However, how about antibacterial properties of other sulfur-containing flavors? How to attenuate the virulence of pathogens by sulfur-containing flavors with strong antibacterial effect? The answers of these questions remain uncertain. Therefore, concerning these questions the objective of this project is to elucidate the molecular mechanism involved in virulence attenuation of sulfur-containing flavors from the points of virulence factor expression and cellullar immunologic response. The tested foodborne pathogens are Staphylococcus aureus, Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella typhimurium in this project. Firstly, a comprehensive and systematic screening of sulfur-containing flavors with strong antibacterial activities is conducted. The proper conditions for virulence attenuation of sulfur-containing flavors are determined by investigation of bacterium metabolic kinetics. Secondly, in order to determine the target virulence molecular, the effects of sulfur containing flavors on gene and protein expressions of virulence factors are investigated by the methods of RT-qPCR and Western blotting. Lastly, the effects of sulfur-containing flavors on cellullar immunologic response induced by pathogens and target toxin are analyzed by molecular biological methods, such as flow cytometry, gene chip, etc. Consequently, the studies of this project will provide foundational information for enriching food preservatives.