Short Chain Fatty Acids Commonly Produced by Gut Microbiota Influence Salmonella enterica Motility, Biofilm Formation, and Gene Expression

Abstract

Short chain fatty acids (SCFAs) are commonly produced by healthy gut microbiota and they have a protective role against enteric pathogens. SCFAs also have direct antimicrobial activity against bacterial pathogens by diffusion across the bacterial membrane and reduction of intracellular pH. Due to this antimicrobial activity, SCFAs have promising applications in human health and food safety. In this study, the minimum inhibitory concentrations (MICs) of four SCFAs (acetic acid, butyric acid, propionic acid, and valeric acid) in Salmonella strains isolated from poultry were determined. The effect of subinhibitory concentrations of SCFAs in Salmonella biofilm formation, motility, and gene expression was also evaluated. Butyric acid, propionic acid, and valeric acid showed a MIC of 3750 µg/mL in all strains tested, while the MIC of acetic acid was between 1875 and 3750 µg/mL. Subinhibitory concentrations of SCFAs significantly (p < 0.05) reduced the motility of all Salmonella strains, especially in the presence of acetic acid. Biofilm formation was also significantly (p < 0.05) lower in the presence of SCFAs in some of the Salmonella strains. Salmonella strain. Salmonella Typhimurium T7 showed significant (p < 0.05) upregulation of important virulence genes, such as invA and hilA, especially in the presence of butyric acid. Therefore, SCFAs are promising substances for the inhibition of the growth of foodborne pathogens. However, it is important to avoid the use of subinhibitory concentrations that could increase the virulence of foodborne pathogen Salmonella.

The Role of Fatty Acid Metabolites in Vaginal Health and Disease: Application to Candidiasis

“…The effect of SCFA against intestinal pathogens, such as Salmonella species, E. coli and Campilobacter jejuni, has been investigated. SCFA modulate growth, motility, biofilm formation and quorum sensing by these organisms (Nakamura et al, 2009;Amrutha et al, 2017;Jacobson et al, 2018;Lamas et al, 2019). Remarkably, it has also been shown that subinhibitory concentrations of these SCFA can alter gene expression of pathogenic bacteria in such a way that virulence is favored (Lamas et al, 2019).…”

Mitigating the Spread and Translocation of Salmonella Enteritidis in Experimentally Infected Broilers under the Influence of Different Flooring Housing Systems and Feed Particle Sizes

“…A previous study discussed an additional beneficial effect of offering a coarse compound feed to broilers reflected in the increased synthesis of butyrate in the large intestine [ 56 ]. This butyrate can reduce the invasive activity of Salmonella [ 32 , 57 ]. There is also evidence that the use of intact cereal grains in compound feed has a positive effect on the microflora in the intestine.…”

The Intestinal Microbiota: Impacts of Antibiotics Therapy, Colonization Resistance, and Diseases

“…SCFAs have direct antimicrobial activity by diffusing through bacterial membranes and lowering intracellular pH. SCFAs have promising applications in human health and food safety due to their antimicrobial activity [ 79 ]. Clostridia SCFAs are important metabolites that inhibit S. Typhimurium growth in mice intestines [ 73 ], pathogenic E. coli strain growth in streptomycin-treated mice [ 80 ], and C. difficile growth in humans [ 81 , 82 ].…”