The gut microbiota has recently been identified as an environmental factor that may promote
metabolic diseases. To investigate the effect of gut microbiota on host energy and lipid
metabolism, we compared the serum metabolome and the lipidomes of serum, adipose
tissue, and liver of conventionally raised (CONV-R) and germ-free mice. The serum
metabolome of CONV-R mice was characterized by increased levels of energy metabolites,
eg, pyruvic acid, citric acid, fumaric acid, and malic acid, while levels of cholesterol and fatty …