沙门氏菌与受污染食品的大量爆发有关,包括乳液。乳液受乳化剂类型和油存在的影响,对细菌有不同程度的压力或保护作用。虽然我们之前的研究表明,乳化剂溶液,而不是乳液,对热处理后的鼠伤寒沙门氏菌有保护作用,潜在机制尚不清楚.本研究选择了鼠伤寒沙门氏菌作为模型微生物,并利用相同的乳化剂(Tween20,Tween80,TritonX-100)创建乳化剂溶液和具有相同油分数(60%(v/v))的乳液,以检查它们对9个选定基因(rpoE,rpoH,otsB,proV,fada,fabA,dnaK,ibpA,ompC)与应激反应相关。具体来说,该研究观察到在55°C的正常和热胁迫下基因表达的变化。孵育20小时后,TritonX-100乳剂引起应激相关基因的上调,rpoe,otsB,还有FabA,暗示紧张的环境。热处理后,TritonX-100溶液中的鼠伤寒沙门氏菌显示出更长的5-log减少时间,proV增加,fabA和ompC表达减少,表明与其乳液相比,热保护得到了增强。相反,吐温80溶液增加fabA和ompC表达,表明更大的膜流动性和被动扩散,潜在地降低热阻。然而,根据ibpA的上调,热休克蛋白的过量产生可能缓解了这种效应.值得注意的是,TritonX-100环境在热处理后表现出最显著的基因表达变化,而没有油的吐温80是最不适合细菌生存的。这些发现告知细菌在各种条件下的反应,协助食品安全战略。
Salmonella has been associated with numerous outbreaks from contaminated food products, including emulsions. Emulsions are influenced by emulsifier type and oil presence, which can have varying degrees of stress or protection on bacteria. Although our previous research has shown that emulsifier solutions, rather than emulsions, provide a protective effect on Salmonella typhimurium after thermal treatment, the underlying mechanism remains unclear. This study selected S. typhimurium as the model microorganism and utilized the same emulsifiers (Tween 20, Tween 80, Triton X-100) to create emulsifier solutions and emulsions with the same oil fraction (60% (v/v)) to examine their effect on the expression of nine selected genes (rpoE, rpoH, otsB, proV, fadA, fabA, dnaK, ibpA, ompC) associated with stress response. Specifically, the study observed variations in gene expression under normal and thermal stress at 55°C. After 20-h incubation, Triton X-100 emulsion caused an upregulation of stress-related genes, rpoE, otsB, and fabA, suggesting stressful environment. After thermal treatment, S. typhimurium in Triton X-100 solution showed a longer 5-log reduction time with increased proV and decreased fabA and ompC expression, suggesting enhanced thermal protection compared to its emulsion. Conversely, Tween 80 solution increased fabA and ompC expression, indicating greater membrane fluidity and passive diffusion, potentially reducing thermal resistance. However, according to the upregulation of ibpA, this effect was likely mitigated by the overproduction of heat shock proteins. Notably, Triton X-100 environments exhibited the most significant gene expression changes after heat treatment, whereas Tween 80 without oil was the most inhospitable for bacterial survival. These findings inform bacterial responses under various conditions, aiding food safety strategies.