Exopolysaccharide from Lactobacillus casei NA-2 attenuates Escherichia coli O157:H7 surface adhesion via modulation of membrane surface properties and adhesion-related gene expression. (December 2022)

• Record Type: Journal Article
• Authors: Ma, Lan; Xu, Xiaoqing; Peng, Qing; Yang, Shuo; Zhang, Yuwei; Tian, Dandan; Shi, Linbo; Qiao, Yu; Shi, Bo
• Is Part Of: Microbial pathogenesis. Volume 173(2022)Part A
• Publication Date: 2022-12
• Subjects: Exopolysaccharide -- Escherichia coli -- Bacterial adhesion -- Surface properties -- Biofilm; Pathogenic microorganisms -- Periodicals; Pathology, Molecular -- Periodicals; Communicable Diseases -- microbiology -- Periodicals; Communicable Diseases -- parasitology -- Periodicals; Micro-organismes pathogènes -- Périodiques; Pathologie moléculaire -- Périodiques; Electronic journals; 616.9041
• DOI: 10.1016/j.micpath.2022.105863
• Languages: English
• ISSNs: 0882-4010

Abstract

Abstract: The natural compound, exopolysaccharide from Lactobacillus casei NA-2 (EPS-cn2), has been shown to inhibit biofilm formation by Escherichia coli O157:H7. Although bacterial adhesion to substrate surfaces is a primary, indispensable step in this process, the mechanisms by which EPS-cn2 can block E. coli O157:H7 adhesion to biotic or abiotic surfaces remain unclear. In this study, investigation of E. coli O157:H7 response to EPS-cn2 revealed that 1 mg/mL EPS-cn2 can decrease adherence to polystyrene and confluent Caco-2 cell surfaces to 49.0% ( P ＜0.0001) and 57.0% ( P ＜0.01) of that in untreated E. coli O157:H7, respectively. Moreover, EPS-cn2 significantly reduced outer membrane hydrophobicity by 49.0% and decreased the electronegativity of the membrane surface charge by as much as 1.57 mV ( P ＜0.05) compared to untreated cells. High throughput RNA sequencing indicated that genes responsible for adhesion through extracellular matrix secretion, such as poly-N-acetyl-glucosamine (PNAG) biosynthesis, locus of enterocyte effacement (LEE) proteins and outer membrane protein (OmpT) were all down-regulated in response to EPS-cn2, while chemotaxis and motility-related flagellar assembly genes were differentially up-regulated, suggesting that the EPS-cn2 may serve as an extracellular signal to attenuate adhesion-related gene expression and alter bacterial surface properties in E. coli O157:H7. These findings support the further development of EPS-cn2 for pathogenic biofilm management in clinical and industrial settings, and suggests the further targeting of adhesion-related genes to limit the persistence of this highly pathogenic strain in sensitive environments. Highlights: EPS-cn2 reduced E.coli O157:H7 adhesion to substrates -by modulating its outer membrane surface properties and adhesion-related gene expression. EPS-cn2 significantly reduced outer membrane hydrophobicity and decreased the electronegativity of the membrane surface charge of E.coli O157:H7. The genes expression levels in E.coli O157:H7 encoding for extracellular matrix, chemotaxis and flagellar assembly changed in response to EPS-cn2. This study supports the development of probiotic exopolysaccharides for pathogenic biofilm management in clinical and industrial settings.