Integrative analysis of the gut microbiota and metabolome in rats treated with rice straw biochar by 16S rRNA gene sequencing and LC/MS-based metabolomics

The intestinal microbiota contributes to host metabolism and health. This study aimed to assess the effects of biochar on cecal microbiome-related metabolic changes in rats. Rats were orally administered rice straw biochar (RSB) at 1120 mg/kg body weight for 5 weeks. Cecal samples were analyzed to perform metabolic and microbial profiling via a combination of 16S rRNA gene sequencing and LC/MS techniques. We observed a significant influence of RSB in shaping the cecal bacterial community, including some potentially beneficial members of phylum Firmicutes belonging to unclassified Lachnospiraceae, Oscillibacter, and Clostridium XlVa and IV, as well as the depletion of some opportunistic pathogens belonging to Prevotella, Bacteroides and Paraprevotella. The metabolomic analysis revealed distinct changes in the cecal metabolic phenotype, including lower levels of L-isoleucine, indole-3-acetic acid, benzoic acid, and tetradecanoic acid as well as higher levels of L-phenylalanine, L-glutamate, 3-phenylpropanoic acid, chenodeoxycholic acid, cholic acid, 7-dehydrocholesterol, (5Z, 8Z, 11Z, 14Z, 17Z)-eicosapentaenoic acid, 11-deoxycorticosterone and retinol, which are mainly involved in the metabolic pathways of linoleic acid, amino acid and steroid hormone biosynthesis. Correlation analysis revealed a positive association of unclassified Lachnospiraceae, Oscillibacter and Clostridium IV with 3-phenylpropanoic acid, L-phenylalanine, L-glutamate, 11-deoxycorticosterone and 7-dehydrocholesterol. These results confirm that the gut microbiome is altered and may be critical for good performance under RSB application by interacting with metabolism.