Modulation de l’action antimicrobienne in vitro d’extraits de plantes en condition de compétition par un dérivé de microbiote d’origine fécale porcine
The incorporation of non-antibiotic antimicrobials compounds to animal feed is extensively used to control the prevalence of pathogens and enhance general gut health. Few plant extracts (PEs) and essential oils (EOs) have a strong antimicrobial effect in vitro which does not concur with the results obtained when the experiment is translated in vivo. This study evaluated the antimicrobial potential of several compounds by agar diffusion assay, tube dilution and by a novel tube dilution method incorporating a pig intestinal microbiota derivative. Results of this study showed that carvacrol, cinnamaldehyde, eugenol and white camphor oil have the same efficiency in the absence or presence of a complex microbiota, thus making these compounds the most relevant for the development of food additives. Metagenomics analyzes were performed to measure the (qualitative) evolution of the microbiota considered under these conditions. Eos concentrations that are higher than the minimal inhibitory concentration (MIC) had a significant impact on both alpha diversity (increase in richness and Eveness) and beta diversity. Furthermore, every EOs, used at high concentration, had a significantly different impact on the microbial structure and composition. Also, qPCR analyses were used to quantify indicators of the intestinal microbiota in the presence of increasing concentrations of EOs; a (significant) decrease of Escherichia coli, stability of Lactobacilli for almost all of the concentrations and a (significant) increase of Lachnospiraceae were observed. Therefore, this study led us to develop an in vitro model which can be used to analyze the efficacy of different organic compounds in the presence of an intestinal microbiota derivative. This suggests that some EOs could have a significantly different impact on the gut microbiota when used at a specific concentration. This feature could be exploited to develop effective food additives with targeted effects.
Antimicrobials Essential oils Food additives Food safety Metagenomics Microbiota Plant extracts Veterinary microbiology