Molecular Characterization of Gut Micro‐flora of Mice Fed Dietary Resistant Starch

Microorganisms in the human gut reach 10 to 100 trillion, and their metabolic activities impact health. Resistant starch (RS) is a fermentable fiber which promotes fermentation in the lower gut. This study investigated how RS impacts the gut microbial community structure. We characterized the gut microflora in mice fed dietary RS using molecular approaches. Total bacterial DNA was isolated from the cecal contents of 2 groups of mice (n=3) fed RS or an equal energy density diet. 16S rRNA was amplified by PCR, cloned, and randomly selected clones were sequenced. Most sequences (≥89%) observed from these treatments were affiliated with two bacterial groups, Firmicutes and Bacteroidetes . Phylum Firmicutes revealed a higher diversity (≥180 operational taxonomic units, OTU), than phylum Bacteroidetes (≥30 OTUs). Firmicutes groups also showed obvious differences in the composition of subgroups based on their phylogenetic relationships between RS and control, while the Bacteroidetes presented a similar composition between the diets. Larger portions (≥50%) of two species belonging to family Lachnospiraceae in the phylum Firmicutes were exclusively detected with RS, implying that these organisms may be closely involved in the RS metabolism. The results provide molecular information on shifts in gut microbial community structures impacted by RS. Supported by LSU AgCenter.