Ability of the gut microbiota to produce PUFA-derived bacterial metabolites: Proof of concept in germ-free versus conventionalized mice

Scope: The gut microbiota is able to modulate host physiology through the production of bioactive metabolites. Our recent studies suggest that changes in gut microbiota composition upon prebiotics supplementation alter tissue levels of PUFA-derived metabolites in mice. However, in vivo evidence that gut microbes produces PUFA-derived metabolites is lacking. This study aimed to decipher the contribution of gut microbes versus that of the host in PUFA-derived metabolite production. Methods and results: To achieve this goal, we compared the proportion of PUFA-derived metabolites and the expression of fatty acid desaturases in germ-free (GF) and conventionalized (CONV) mice fed either a low fat or Western diet. Higher concentrations of PUFA-derived metabolites were found in the colonic contents of conventionalized mice (CONV) mice compared to GF mice. The abundance of these metabolites in host tissues was modulated by dietary treatments but not by microbial status. Although microbial status did significantly influence desaturase expression, no correlations between host enzymes and tissue PUFA-derived metabolite levels were observed. Conclusion: Together, these results highlight the ability of the gut microbiota to produce PUFA-derived metabolites from dietary PUFA. However, microbial production of these metabolites in colonic contents is not necessarily associated with modifications of their concentration in host tissues.