Table 1 Examples of microorganisms found within the gastrointestinal tract of the human lower intestine, the substrates utilized by the bacteria, and products made from the substrates
From: The functionality of the gastrointestinal microbiome in non-human animals
Domain | Taxa | Nitrogen source | Carbon source | Products made | Metabolic potential |
|---|---|---|---|---|---|
Archaea | Methanobrevibacter smithii | Ammonium | Carbon dioxide | Methane | Sulfate reducers Polysaccharide fermentation |
Methanosphaera | Ammonium | – | Methane | Sulfate reducers | |
Bacteria | Actinomyces sp. | – | d-Glucose, d-mannose, starch, dextrin Glycerol | Formate, acetate, succinate, lactate Various antibiotics | Breakdown and recycle organic compounds |
Bacteroides spp. | Ammonium | Starch, cellulose, xylan, pectin, dextran Mucin | Succinate, propionate, acetate, lactate, formate, and malate | Sugar fermentation Increased N source by recycling uric acid waste | |
Bifidobacterium | Ammonium | Glucose, starch, xylan, pectin, inulin, fructose, galactose | Acetate, lactate, acetone, thiamine, folic acid, nicotinic acid, pyridoxine, biotin Conjugated linoleic acid, vitamins | Vitamin biosynthesis Carbohydrate fermentation | |
Clostridium | Amino acids | Glucose, starch, mucin, hyaluronic acid | Acetate, butyrate, acetone, butanol | Proteolytic activity | |
Desulfovibrio | Ammonium | – | Hydrogen sulfide Acetate/ATP | Sulfate reducers | |
Enterococcus | Collagen, casein, insulin, Hb, fibrogen, gelatin | Glucose | Lactate | Lipoprotein lipase inhibitor Proteolytic activity Polysaccharolytic activity | |
Escherichia coli | – | Glucose, OS* | Acetic acid, lactic acid, succinic acid, CO2, H2 | Carbohydrates fermentation | |
Eubacterium | Amino acids | Glucose, OS* | Lactate, acetate, formate, succinate | Metabolism of carbohydrates Lactate-utilizing bacteria | |
Fusobacterium sp. | Amino acids | OS* | Butyrate | Proteolytic activity | |
Lactobacillus sp. | Amino acids | Lactose, OS* | Lactate, acetate | Bile deconjugating activity Folate production | |
Pediococcus sp. | Â | Lactose, OS* | Lactate | Sugar fermentation Immunomodulatory effects | |
Prevotella sp. | Dipeptides, amino acids | Pentose, hexose | Acetate, formate, succinate | Mucin glycoprotein degraders | |
Propionibacterium sp. | Ammonium | Lactose β-Galactosidase | Propionic acid Fatty acids Vitamin B12 Branched-chain acids Short-chain fatty acids | Immunomodulatory effects Lipolysis of glycerides Catabolism of amino acids | |
Ruminococcus | Ammonium | Various carbohydrates | Formate, lactate, succinate | Mucin degraders | |
Staphylococcus | – | Lactose, OS* | Lactic acid | Glucose fermentation Nitrate reductase and urease activity | |
Streptococcus sp. | – | Various sugars, soluble starch | Lactate | Polysacharolytic activity | |
Veillonella sp. | Amino acids | Lactate | Propionate, acetate | Lactate-utilizing bacteria |