基于转录组学分析酸胁迫影响鼠伤寒沙门氏菌耐酸能力的机理

Global Transcriptomic Analysis of Acid-adapted Salmonella typhimurium by RNA Sequencing

目的:探究酸胁迫和非酸胁迫条件下鼠伤寒沙门氏菌(Salmonella typhimurium)的转录组反应,分析差异基因(differentially expressed genes,DEGs)表达水平,阐明酸胁迫影响鼠伤寒沙门氏菌耐酸反应(acid tolerance response,ATR)的相关代谢通路。方法:对鼠伤寒沙门氏菌进行酸胁迫处理,利用转录组测序技术和生物信息学分析相关DEGs,并通过实时聚合酶链式反应(real-time polymerase chain reaction,real-time PCR)进行验证。结果:经酸胁迫后,共筛选到683个DEGs,其中上调343个,下调340个。其中涉及细胞运动、氨基酸代谢、细胞膜组成等通路上调能够使鼠伤寒沙门氏菌快速适应酸环境;碳水化合物代谢相关通路上调能够为鼠伤寒沙门氏菌快速适应酸环境提供更多的能量,与此同时,嘧啶代谢等能量代谢通路下调能够使鼠伤寒沙门氏菌降低能量消耗以维持上述的必需代谢过程;细菌应激调控相关通路上调赋予鼠伤寒沙门氏菌交叉保护抗性;鞭毛、外膜蛋白、脂多糖等毒力相关基因表达上调增强了鼠伤寒沙门氏菌的毒力。real-time PCR验证结果与转录组测序分析表达趋势一致。结论:酸胁迫显著提高了鼠伤寒沙门氏菌的耐酸能力,其中与代谢和细胞过程相关的通路发挥主要作用,本研究结果为进一步了解该菌的酸胁迫反应及更好地控制其在食品中的污染提供了理论依据。

Objective:The purpose of this research was to explore the global transcriptome response of Salmonella typhimurium under acid stress and non-acid stress conditions,analyze the expression levels of differentially expressed genes(DEGs),and elucidate the metabolic pathways related to the acid tolerance response(ATR)of S.typhimurium.Methods:Transcriptome sequencing and bioinformatics were used to select the ATR-related DEGs,whcih were then verified by real-time polymerase chain reaction(real-time PCR).Results:In response to acid stress,a total of 683 DEGs were identified in S.typhimurium,including 343 up-regulated and 340 down-regulated ones.The DEGs involved in cell movements,amino acid metabolism,and cell membrane composition were up-regulated,thus making S.typhimurium adapt to the acidic environment quickly.The up-regulation of the genes associated with carbohydrate metabolism could provide more energy for S.typhimurium to adapt to the acidic environment rapidly.Meanwhile,the down-regulation of the genes involved in energy metabolism pathways such as pyrimidine metabolism could reduce the energy consumption of S.typhimurium to maintain these essential metabolic processes.The up-regulation of the genes related to stress reponse response could enhance the cross-protective resistance of S.typhimurium,and the up-regulation of the virulence-related genes such as flagella,outer membrane protein,and lipopolysaccharide could strengthen the virulence of acid-adpted S.typhimurium.Additionally,the results of real-time PCR were consistent with these transcriptomic data.Conclusion:Acid stress can significantly enhance the acid tolerance of S.typhimurium,and the signaling pathways related to metabolism and cellular processes may play major roles in this effect.This study provides a theoretical basis for further understanding the ATR of S.typhimurium and better controlling its contamination in foods.