Modulation of Gut Microbiota and Short-Chain Fatty Acid Production by Simulated Gastrointestinal Digests from Microalga Chlorella vulgaris

<i>Chlorella vulgaris</i> is a source of potential bioactive compounds that can reach the large intestine and interact with colonic microbiota. However, the effects of consumption of this microalga on gastrointestinal function have scarcely been studied. This paper simulates, for the first time, the passage of <i>C. vulgaris</i> through the gastrointestinal tract, combining the INFOGEST method and in vitro colonic fermentation to evaluate potential effects on the human colonic microbiota composition by 16S rRNA gene sequencing and its metabolic functionality. The results show that the presence of this microalga increased the release of short-chain fatty acids (SCFAs), such as acetic, propionic, butyric, and isobutyric fatty acids, after 48 h colonic fermentation, being indicators of gut health. In correlation with the release of SCFAs, a significant reduction in bacterial groups causing intestinal imbalance, such as <i>Enterobacteriaceae</i>, <i>Enterococcus</i> spp., and <i>Staphylococcus</i> spp., was observed. In addition, digests from <i>C. vulgaris</i> favored intestinal health-related taxa, such as <i>Akkermansia</i> and <i>Lactobacillus</i>. <i>C. vulgaris</i> is, therefore, a promising food ingredient for good intestinal health and the maintenance of a balanced colonic microbiota.