total population ~10^14cells: Num. of species ~500-1,000: total mass ~1.5kg
||Human Homo sapiens
||Rubio CA. The Natural Antimicrobial Enzyme Lysozyme is Up-Regulated in Gastrointestinal Inflammatory Conditions. Pathogens. 2014 Jan 16 3(1):73-92. doi: 10.3390/pathogens3010073. p.74 2nd paragraphPubMed ID25437608
|| Kaper, J.B. Sperandio, V. Bacterial cell-to-cell signaling in the gastrointestinal tract. Infect. Immun. 2005, 73, 3197–3209.PubMed ID15908344
||P.74 2nd paragraph:"The density of the bacterial flora in the GI tract is huge: it varies from 10^3/mL near the gastric outlet, to 10^10/mL at the ileo-cecal valve, to 10^11 to 10^12/mL in the colon. The total microbial population (ca. 10^14) [primary source] exceeds the total number of cells in the GI tract. About 500 to 1,000 different species exist, a biomass that weights about 1.5 kg [primary source]."