median water content 516±12fg: median dry mass content 203±5fg: median total mass content 727±15fg fg
||Bacteria Escherichia coli
||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
||"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."
||"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.