Prevotella-type gut microbiota of healthy persons is responsive to dietary fiber interventions
Current dietary guidelines do not consider the variety of compositional, structural and functional differences of dietary fibers (DF). DF are prerequisite of various beneficial metabolites produced by the gut microbiota, including short chain fatty acids (SCFA). This study focuses on the modulatory effects of beta-glucan, rye bran and two DF-mixes on the compositional changes of fecal microbiome of 12 healthy subjects in a 5-months multi-intervention nutrition trial. Up to 28 fecal samples per each participant were analyzed for pH, organic acid content by HPLC and microbiota by 16S ribosomal gene sequencing. Five distinct microbiome types were detected based on the dominant bacterial taxa: Prevotella, Bacteroides, Phascolarctobacterium, Fusicatenibacterium and Christensenella while each type could be characterized by distinct accompanying microbial patterns. The Prevotella-type microbiota responded to all tested dietary fibers, while the Bacteroides-type microbiota was the most stable. Enhancement of the growth of Parabacteroides by rye bran and that of Roseburia by mixed soluble fibers were common among the participants (in 83 % and 58 % of participants, respectively). Over 900 significant shifts in abundances of detected bacterial taxa were observed at an individual level. The pH of all fecal samples varied between 6.1 and 8.3 and correlated, in most cases, with the amounts of SCFA and microbial composition. The effect of DF on the metabolism of fecal microbiota clearly depended on the individual microbiota type. Combining the analysis of gut microbiota dynamics and knowledge on properties of DFs would provide a powerful strategy for nutrition guidance and disease prevention.