Cell water content, dry content and total content (determined separately) in early stationary phase

Range median water content 516±12fg: median dry mass content 203±5fg: median total mass content 727±15fg fg
Organism Bacteria Escherichia coli
Reference Feijó Delgado et al., Intracellular water exchange for measuring the dry mass, water mass and changes in chemical composition of living cells. PLoS One. 2013 Jul 2 8(7):e67590. doi: 10.1371/journal.pone.0067590 p.2 right column 3rd paragraphPubMed ID23844039
Method "As an initial test of [researchers'] method, [they] separately determined the water content, dry content and total content of individual cells from a sample of early stationary E. coli. Since the measurement time typically exceeded several doublings of the culture, cells were fixed to ensure all cells were representative of the culture at a single timepoint. [Researchers] measured the single-cell water mass distribution by sequentially measuring the cells in OptiPrep:PBS (?=1.101g/cm^3) followed by D2O:PBS (?=1.101g/cm^3). The median water content in these cells was 516±12fg. [They] then measured cells sequentially in H2O:PBS (?=1.005g/cm^3) and D2O:PBS to obtain the dry mass distribution, yielding a median value of 203±5fg. Finally, [they] measured the total mass distribution by the method of Grover et al., 2011 [PMID 21690360] and the median value was 727±15fg. To ensure that the osmotic pressure experienced by the cells was equal in both fluids of each measurement, phosphate buffered saline (PBS) was added to all the solutions in order to match their osmolarity."
Comments "The results presented above [in measurement method section] demonstrate that the method is selfconsistent, as the water content of the cells plus the dry mass (sum of median values equals 719±13fg) accounts for the total mass value (Fig. 1c). This suggests the median early stationary fixed E. coli cell is roughly 28% dry material by mass and 20% by volume, though these numbers may be different in living cells." Depends strongly on cell type/growth rate etc.
Entered by Uri M
ID 111210