Age-related functional changes of intestinal flora in rats.

Intestinal flora structure and function change with age and have been associated with a variety of aging-related diseases. Until now, how age affects the functions of gut bacteria has not been fully understood. We used 16S-rRNA-sequencing technology and PICRUSt2 analysis to predict the functions encoded by intestinal flora in male Wistar rats across lifespan. We found that the abundance of gut microbiota genes encoding the L-tryptophan, L-histidine, L-leucine, inositol and catechol degradation pathways as well as L-arginine, ectoine, flavin and ubiquinol synthesis pathways increased with age. Differential analysis of the associated genera revealed that Rhodococcus spp. were significantly abundant during middle-old aged stage. This genus contributed greatly to the L-tryptophan, catechol and inositol degradation pathways as well as ectoine and L-arginine biosynthesis pathways. We concluded that gut bacteria-encoded functions such as amino acid metabolism, B vitamin metabolism, aromatic compound metabolism and energy metabolism varied in an age-dependent manner, and Rhodococcus spp. were the most associated functional bacteria in middle-old aged rats. These may be closely associated with the physiological phenotype of the aging process, which offers new insights for evaluating the relationship between intestinal flora and aging.