Transcriptomic analysis of Listeria monocytogenes aerobic conditions at pH 5.5

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.