Transcriptomic analysis of Listeria monocytogenes in response to bile under aerobic and anaerobic conditions

Listeria monocytogenes is a gram positive facultative anaerobic bacterium that causes the food borne illness listeriosis. The pathogenesis of this bacterium depends on its survival in anaerobic, acidic and bile conditions encountered throughout the gastrointestinal tract. This transcriptomics study was conducted to analyze the differential gene expression under conditions mimicking the gastrointestinal tract. Changes in gene expression were analyzed using RNA isolated from L. monocytogenes strain F2365 at both aerobic and anaerobic conditions, upon exposure to 0% and 1% bile at acidic and neutral pH. Genes responsible for pathogenesis, cell wall associated proteins, DNA repair, transcription factors, stress response were differentially expressed under various conditions mimicking the gastrointestinal tract. Upon exposure to anaerobiosis in acidic conditions, the expression of genes encoding the virulence factors internalins, listeriolysin O, etc. were differentially expressed, as well as many histidine sensory kinases. These data indicate that the response to anaerobiosis influences the expression of genes related to the survival of L. monocytogenes under acidic and bile conditions. Further research is needed to decipher the role of oxygen in pathogenesis of L. monocytogenes.

单核细胞增生李斯特菌（Listeria monocytogenes）是一种革兰氏阳性兼性厌氧菌，可引发食源性疾病李斯特菌病（listeriosis）。该菌的致病机制依赖于其在胃肠道全程所遭遇的厌氧、酸性及胆汁环境中的存活能力。本转录组学（transcriptomics）研究旨在分析模拟胃肠道环境下的差异基因表达情况。实验采用从单核细胞增生李斯特菌菌株F2365中分离的RNA，分析了有氧、厌氧条件下，分别暴露于0%与1%胆汁、酸性及中性pH环境时的基因表达变化。在多种模拟胃肠道的环境条件下，与致病机制、细胞壁相关蛋白、DNA修复、转录因子及应激反应相关的基因均呈现差异表达。当在酸性环境中暴露于厌氧条件时，编码内化素（internalins）、李斯特溶血素O（listeriolysin O）等毒力因子的基因，以及大量组氨酸感应激酶（histidine sensory kinases）的表达均发生显著变化。上述数据表明，对厌氧环境的应答会影响单核细胞增生李斯特菌在酸性及胆汁环境下的存活相关基因的表达。后续仍需开展进一步研究，以阐明氧气在单核细胞增生李斯特菌致病机制中的作用。