Table 1. Bounds for bacteria number in different organs, derived from bacterial concentrations and volume.
Location | Typical concentration of bacteria (1)(number/mL content) | Volume (mL) | Order of magnitude bound for bacteria number |
---|---|---|---|
Colon (large intestine) | 1011 | 400 (2) | 1014 |
Dental plaque | 1011 | <10 | 1012 |
Ileum (lower small intestine) | 108 | 400 (5) | 1011 |
Saliva | 109 | <100 | 1011 |
Skin | <1011 per m2 (3) | 1.8 m2 (4) | 1011 |
Stomach | 103–104 | 250 (5)–900 (6) | 107 |
Duodenum and Jejunum (upper small intestine) | 103–104 | 400 (5) | 107 |
(1) Except for skin, concentrations are according to [9]. For the skin, we used bacterial areal density and total skin surface to reach an upper bound.
(2) See derivation in section below.
(3) Skin surface bacteria density is taken from [11].
(4) Skin area calculated as inferred from standard formula by DuBois for the body surface area [12].
(5) Volume of the organs of the gastrointestinal tract is derived from weights taken from [13] by assuming content density of 1.04 g/mL [6].
(6) Higher value is given in [14].