Synergistic inhibition of Listeria monocytogenes by salami salt and bile salts during digestion via ribosomal and glycolytic pathway downregulation.

The presence of food, combined with the gastrointestinal environmental condition, may affect the physiological state of L. monocytogenes during digestion, while the mechanism of food ingredients on this pathogen under the simulated digestive tract was not fully elucidated. Therefore, this study investigated the impact of salami on L. monocytogenes survival during in vitro digestion and identified the inhibitory factors from both food and gastrointestinal environments, further exploring their synergistic mechanism through transcriptomic analysis. Results revealed that, in the presence of salami, decreased survival counts of L. monocytogenes were observed after digestion. Furthermore, the expression of virulence genes (prfA, inlA, inlB, actA, hly) of L. monocytogenes in the salami was significantly lower than that of the control group under the gastrointestinal environment, accompanied by the reduction of listeriolysin O (LLO) production. The inhibited factors analysis identified salt ingredients as the primary inhibitory component, combined with intestinal bile salts, to weaken the survival capacity of L. monocytogenes in the intestinal digestion. Additionally, compared with other groups, results of transcriptomic demonstrated that the genes related to ribosomal proteins and glycolysis in L. monocytogenes treated with bile salts and 2.50% salts were down-regulated, which may further affect the protein translation activities and ATP production of pathogens. Meanwhile, the ATP production of L. monocytogenes was significantly decreased compared with other groups, which confirmed the transcriptomic results. All in all, this study could provide new insights into the interaction between food components and gastrointestinal environmental factors in the mechanism of pathogen survival inhibition.