Fraction of cell mass that is water

Value 68.1 % Range: ±1.2 %
Organism Bacteria Arthrobacter sp.
Reference Illmer P, Erlebach C, Schinner F. A practicable and accurate method to differentiate between intra- and extracellular water of microbial cells. FEMS Microbiol Lett. 1999 Sep 1 178(1):135-9. Table 1 Table - link PubMed ID10483732
Primary Source Uribelarrea, J.L., Pacaud, S., Goma, G. (1985) New method for measuring the cell water content by thermogravimetry. Biotechnol. Lett. 7, 75–80
Method A thermographimetric method-An infra-red balance (Mettler LP16) which was interfaced to a computer was used for the investigation. Weight was measured automatically every 6 s till no further change in weight could be recognised (about 40 min after starting). The basic assumption of the method is that drying of microbial cells occurs during two phases (Fig. 1). First, the more volatile extracellular water We is lost. Not before this fraction is completely evaporated, the intracellular water Wi starts to vaporise. The change between the two phases (the so-called critical point, CP) can be detected in the form of a small bulge. This change in drying behaviour should be caused by the membrane and/or the cell wall as this briefly protects Wi against evaporation. Researchers used the second derivation (f"(x)) to determine the CP. As can be deduced from Fig. 1, the CP must be located between two inflection points (f"(x)=0) and should be characterised by a minimum of f"(x) which indicates a minimum radius of curvature of the original curve. See primary source for details of method.
Comments In Bactopeptone solution. See table link for water fraction of cell mass in SES and STI media.
Entered by Uri M
ID 105093