Suppressive effect ofLactobacillus fermentumLim2 onClostridioides difficile027 toxin production

Abstract

Clostridioides difficile is a spore‐forming, Gram‐positive, anaerobic pathogen that caused gastrointestinal illness. During dysbiosis, overgrowth of C. difficile resulting in higher levels of toxin production. Since Lactobacillus has been commonly used to alleviate gastrointestinal discomfort, this study aimed to investigate the effects of Lactobacillus isolated from kimchi on the quorum‐sensing and virulence factors of C. difficile 027. Among the isolated Lactobacillus strains, the acid and bile tolerant L. fermentum Lim2 was only able to reduce C. difficile 027 growth by one log10 CFU per ml. In keeping with this finding, C. difficile 027 growth was unaffected by either untreated or heat‐inactivated cell extracts from L. fermentum Lim2. Both untreated and heat‐inactivated cell extracts did, however, significantly reduce the autoinducer‐2 (AI‐2) activity of C. difficile 027, with the most prominent suppression effect (654‐fold) being found from 100 mg ml−1 of heat‐inactivated cell extract. A gene expression analysis indicated that in the presence of 100 mg ml−1 heat‐inactivated cell extract, the quorum‐sensing (luxS) and the virulence factors (tcdA, tcdB and tcdE) were significantly suppressed, whereas the negative regulator gene (tcdC) was significantly up‐regulated. Taken together, the significant anti‐pathogenic effect from L. fermentum Lim2 could potentially be used to treat C. difficile‐infections. Significance and Impact of the Study Clostridioides difficile is a Gram‐positive pathogenic bacteria that caused gastrointestinal illness via toxic production. The emergence of highly virulence and foodborne C. difficile strains has further increased the incident and severity of C. difficile‐infections (CDIs). Numerous studies have reported the immunomodulatory activity of Lactobacillus, a member of healthy gut microbiota, to maintain gastrointestinal health. Here, we successfully isolated L. fermentum Lim2 from kimchi, and identified a promising anti‐pathogenic effect against C. difficile 027, from the heat‐inactivated L. fermentum cell extract via suppression on the C. difficile 027 quorum‐sensing system and toxin production, which could potentially be used to treat and prevent CDIs.

Quorum-Sensing Inhibition by Gram-Positive Bacteria

“…Among other Gram-positive pathogenic bacteria, QS in Listeria monocytogenes was inhibited by the metabolites of L. plantarum M.2 and Lactobacillus curvatus B.67 (reclassified as Latilactobacillus curvatus) due to inhibition of agr genes [65]. A similar mechanism has been noted for C. difficile, which has been shown to inhibit AI-2 and the QS (luxS) system upon adding heat-treated supernatant L. fermentum Lim2 [66]. These data may indicate the low molecular nature of the metabolites involved in QQ of Gram-positive bacteria in lactobacilli.…”

Lacticaseibacillus casei Strain T21 Attenuates Clostridioides difficile Infection in a Murine Model Through Reduction of Inflammation and Gut Dysbiosis With Decreased Toxin Lethality and Enhanced Mucin Production

“…Since C. difficile toxins are mainly responsible for the pathogenesis of CDI, an interference in toxin effect might be another mechanism to be considered for C. difficile attenuation ( Kolling et al, 2012 ; Panpetch et al, 2019 ; Yong et al, 2019 ). C. difficile toxins inactivate Rho GTPases resulting in gut leakage, intestinal inflammation, and cell death ( Chen et al, 2015 ).…”

Limosilactobacillus fermentum from buffalo milk is suitable for potential biotechnological process development and inhibits Helicobacter pylori in a gastric epithelial cell model

“…L. fermentum is a widely studied probiotic, however, distinct strains often differ in terms of physiology and biological properties [ 6 , 11 , [35] , [36] , [37] , 42 , 48 , 54 , 57 , 60 ]. The aim of this study was to develop an improved fermentation process and demonstrate its suitability for scale-up and subsequent concentration, including the drying process, for the potential industrial production of viable biomass by using a L. fermentum strain, that was newly isolated from buffalo milk, as test example.…”