Development of a simultaneous quantification method for the gut microbiota-derived core nutrient metabolome in mice and its application in studying host-microbiota interaction.

The gut microbiota interacts with the host via production of various metabolites of dietary nutrients. Herein, we proposed the concept of the gut microbiota-derived core nutrient metabolome, which covers 43 metabolites in carbohydrate metabolism, glycolysis, tricarboxylic acid cycle and amino acid metabolism, and established a quantitative UPLC-Q/TOF-MS method through 3-nitrophenylhydrazine derivatization to investigate the influence of obesity on the gut microbiota in mice. All metabolites could be simultaneously analyzed via separation on a BEH C18 column within 18 min. The lower limits of quantification of most analytes were less than 1 µM. Validation results demonstrated suitability for the analysis of mouse fecal samples. The method was then applied to detect the gut microbiota-derived nutrient metabolome in the feces of high-fat diet induced obese (DIO) and ob/ob (leptin-deficient) mice, as well as obesity-prone (OP) and obesity-resistant (OR) mice. Compared to the control groups, there were 13, 23 and 10 differentially abundant metabolites detected in ob/ob, DIO and OP groups, respectively. Among them, amino acids including leucine, isoleucine, glycine, methionine, tyrosine and glutamine were co-downregulated in the obese or OP mice and exhibited inverse association with body weight. 16S rDNA analysis revealed that the genera Lactobacillus and Dubosiella were also inversely associated with body weight and positively correlated with fecal amino acids. Collectively, our work provides an effective and simplified method for simultaneous quantifying the gut microbiota-derived core nutrient metabolome in mouse feces, which could assist various future studies on host-microbiota metabolic interaction.