Genome-centric investigation of the potential succession pattern in gut microbiota and altered functions under high-protein diet.

Excessive intake of protein has been considered as a factor leading to intestinal microecological disorder, but why and how intestinal microbes change under the high-protein diet (HPD) have yet to be fully elucidated. Here, we performed 16S rRNA gene amplicon sequencing and metagenomic sequencing on contents of cecum, colon and feces from two groups of mice with standard diet (SD) and HPD. And then the microbial alteration of composition and function were deeply analyzed by using several statistical models and bioinformatic methods. Among the three niches, the microbes in the colon are observed to show the most significant change with lower alpha-diversity and higher beta-diversity after HPD. In addition, this alteration of microbial structure may be related to the replacement process and co-occurring community. Most species are also enriched or impoverished in the colon during this process. After analyzing the functional genes related to protein and carbohydrate hydrolysis in different niches, we found that the carbon source provided by poor carbohydrates compared with the rich protein may be the potential factor driving the enrichment of mucin degraders and desulphaters in the colon under HPD. Therefore, our study provided a new insight to understand the underlying mechanism of HPD affecting intestinal health from the perspective of microbial functional ecology.