Effects of short-chain fatty acids on Aliarcobacter butzleri’s virulence

• Autor(a) principal: Fonseca, Inês Maria Duarte da
• Data de Publicação: 2024
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Texto Completo: http://hdl.handle.net/10400.6/14585
• topic: Ácidos Gordos de Cadeia Curta; Adesão; Aliarcobacter Butzleri; Biofilmes; Genes Putativos de Virulência; Invasão.; Motilidade; Viabilidade Celular; Virulência

Aliarcobacter butzleri has commonly been associated with diseases in both humans and animals and is therefore classified as a moderate hazard to human health. This bacterium may be found in various environments on a large scale, such as soils, waters and the food chain, being a major source of transmission and contamination. Moreover, it has been associated with diarrheal and non-diarrheal gastrointestinal diseases, whose main symptoms include abdominal pain, nausea and fever. Despite the research available on this microorganism, its response to host’s resistance colonization mechanisms remain underexplored. Short-chain fatty acids (SCFA) have been taken into study as mechanisms of resistance to colonization and are produced through the microbial fermentation of non-digestible carbohydrates in the intestine, being responsible for the maintenance of intestinal and metabolic health in humans. As SFCA are one of the multiple adverse conditions A. butzleri faces until it reaches its preferred colonization site, the intestine, this work aims to evaluate the effects of SCFA on the virulence and survival of this bacterium. Therefore, the bacterium’s growth, gene expression, motility, biofilm formation and adhesion and invasion abilities were evaluated with different types and concentrations of SCFA. The majority of the assays were conducted with eight A. butzleri isolates and, in general, lower concentrations showed no significant effect on bacterial growth, whereas the higher concentrations revealed an increase of the lag phase and/or growth inhibition, in a strain-dependent manner. Regarding the evaluation of putative virulence genes expression, it was observed an overexpression by most concentrations tested for the flaA and luxS genes. At a concentration of 130mM_SCFA, the ciaB gene also displayed an overexpression. The motility of most strains used in the study presented a decrease in this virulence factor. Also, the results of the biofilm formation of this bacterium showed a strain-dependence considering the concentration used. Furthermore, the SCFA tested appeared to affect the bacterium’s ability to adhere and invade the Caco-2 cell line, showing a trend to reduce these virulence features. Altogether, through the analysis of the results obtained from this study, it is noticeable that SCFA present a modulatory effect on A. butzleri’ survival and virulence, in a straindependent form. Regardless, it is possible to conclude that SCFA have an important role during the infection process, with the modulation of A. butzleri’ virulence being a point for further investigation.