Effects of Algae Feeding on Mouse Metabolome
Algae are a rich source of macronutrients and micronutrients, but metabolic impact of algae feeding on animals is not well defined. In this study, 3 groups of mice were fed AIN93G substituted with 0, 5% or 20% dried powder of a fresh water green algae (Scenedemus spp.). Serum, urine, fecal and tissue samples were collected at the end of 4-week treatments. Metabolic changes were evaluated by growth performance, blood chemistry and untargeted metabolomics. Compared with control diet, feeding 5% algae increased daily weight gain and feed intake (P < 0.01) while 20% algae decreased both parameters (P < 0.01). Serum glucose, triglyceride, and blood urea nitrogen levels were not affected by algae feeding, except serum cholesterol level was reduced by feeding 20% algae (P < 0.01). Metabolomic analysis identified diverse metabolic changes after algae feeding. The metabolites affected by 5% and 20% algae feeding include porphyrin pigments and bile acid metabolites in feces, free threonine and lysine in serum, glycine conjugates of medium-chain fatty acids and bacterial metabolites in urine. In addition, 20% algae also increased the levels of water-soluble vitamins in urine and long-chain fatty acids in feces, while decreased the levels of free aspartate, glutamate and taurine in serum and triglycerides in liver. Those observations suggest that feeding algae leads to dose-dependent changes in amino acid, lipid and bacterial metabolism, which could be the causes or the consequences of observed changes in growth and feed intake.