Number of microbial cells in human body

Range 10^14 (see BNID 113000 for more updated value of 3.8x10^13) microbial cells (mostly bacteria)/human body
Organism Human Homo sapiens
Reference Savage DC. Microbial ecology of the gastrointestinal tract. Annu Rev Microbiol. 1977 31: 107-33. p. 107 top paragraphPubMed ID334036
Primary Source [70] Luckey TD. Introduction to intestinal microecology. Am J Clin Nutr. 1972 Dec25(12):1292-4.PubMed ID4639749
Method (Primary source 2nd paragraph:) "Adult man carries 10^12 microbes associated with his epidermis and 10^14 microbes in his alimentary tract (Fig. 1). The latter number is based upon 10^11 microbes/g contents of an alimentary tract with a capacity of approximately 1 liter."
Comments P.107 top paragraph: "The adult human organism is said to be composed of approximately 10^13 eukaryotic animal cells (BNID 102390). That statement is only an expression of a particular point of view. The various body surfaces and the gastrointestinal canals of human maybe colonized by as many as 10^14 indigenous prokaryotic and eukaryotic microbial cells (primary source). These microbes profoundly influence some of the physiological processes of their animal host (refs 49, 103). From another point of view, therefore, the normal human organism can be said to be composed of over 10^14 cells, of which only about 10% are animal cells." For 10^14 bacteria in vertebrate intestine see Steinhoff 2005 PMID 15894105 p.12 left column: "The intestine of vertebrates is the most complex and densely populated ecosystem that may comprise all forms of living communities including mutualism, commensalism and parasitism. Approximately, 10^14 bacteria belonging to more than 500 different bacterial species live in a thermostabile and nutrient rich environment. Thus, strict rules of community life and growth control must exist in order to maintain a healthy milieu in the intestine."
Entered by Uri M
ID 102392