Transcriptomic Analysis of Listeria monocytogenes in Response to Bile Under Aerobic and Anaerobic Conditions

Abstract

Listeria monocytogenes is a gram-positive facultative anaerobic bacterium that causes the foodborne illness listeriosis. The pathogenesis of this bacterium depends on its survival in anaerobic, acidic, and bile conditions encountered throughout the gastrointestinal (GI) tract. This transcriptomics study was conducted to analyze the differences in transcript levels produced under conditions mimicking the GI tract. Changes in transcript levels 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. Transcripts corresponding to genes responsible for pathogenesis, cell wall associated proteins, DNA repair, transcription factors, and stress responses had variations in levels under the conditions tested. Upon exposure to anaerobiosis in acidic conditions, there were variations in the transcript levels for the virulence factors internalins, listeriolysin O, etc., as well as many histidine sensory kinases. These data indicate that the response to anaerobiosis differentially influences the transcription of several genes related to the survival of L. monocytogenes under acidic and bile conditions. Though further research is needed to decipher the role of oxygen in pathogenesis of L. monocytogenes, these data provide comprehensive information on how this pathogen responds to the GI tract.

A comprehensive investigation of protein expression profiles in L. monocytogenes exposed to thermal abuse, mild acid, and salt stress conditions

“…AtpF is a subunit of plasma membrane proton-transporting ATP synthase complex coupling factor (F) 0, which is responsible for generating ATP by using the proton motive force across the bacterial membrane and contributes to facing acidity stress in L. monocytogenes by maintaining membrane potential and pH homeostasis (Bucur et al, 2018). In C3, AtpF was connected to AtpB, which seems to be overexpressed in response to various stress conditions, such as low pH combined with anaerobiosis, and in this study was expressed to face thermal abuse (Chakravarty et al, 2021).…”

Two Permeases Associated with the Multifunctional CtaP Cysteine Transport System in Listeria monocytogenes Play Distinct Roles in Pathogenesis

“…Dtp is associated with the transport of dipeptides and tripeptides ( 26 ), while the Opp transport system has been associated with the import of peptides ranging from 4 to 35 amino acids in length ( 27 , 28 ). In addition to peptide import as a source of amino acids, peptide transport systems have been associated with a variety of other functions that include bacterial quorum sensing and signal transduction, recycling of peptidoglycan fragments, adherence to eukaryotic cells, alterations in antibiotic susceptibility, survival under stress conditions, hemolytic activity, and modulation of the activity of the central virulence regulator, PrfA ( 29 – 39 ).…”