mass of bacteria

Em ekhatipoREMOVE at
Wed Apr 10 00:33:32 EST 2002

I should correct myself and appologize to you guys for posting incorrect
information. I finally found my 6-year old calculations and they show (for
photosynthetic bacterium Rhodobacter spheroides - ~1um diameter): 1ml of the
culture at OD660=1 (recalculated from dilutions measured at OD~0.5) contains
about 1.25x10^9 (NOT 10^6 as I previously posted) cells and that corresponds
to ~0.2 mg of extractable portein or 0.5 mg of dry cells. From that follows
that one dried  cell would weigh at ~ 4x10^-10 mg or ~4x10^-13 g. If the
cells consist of 70% water then weight of one wet cell is 9.3x10^9 - almost
exactly as NEB reference sais. Oh, I am relieved I did not screw up back
then :-) The protein data support this figure, because it is known that only
~30-40% of cell protein can be extracted by water-based buffers.

"Em" <ekhatipoREMOVE at> wrote in message
news:%dbs8.34$s4.2488 at
> "Nicholas Landau" <njl2q at> wrote in message
> news:3CB11E37.D05743F9 at
> >
> > For what it is worth, Neidhardt et al. do list a figure for the dry
> of a
> > single E. coli cell in their microbial physiology text."  The figure
> list
> > is 2.9 E-13 g.  The do not include any citations for this figure
> specifically,
> > but they do state that it is "an average of many measurements..."
> Neidhardt,
> > F.C., J. L. Ingraham, and M. Schaecher.  1990.  Physiology of the
> Bacterial
> > Cell.  Sunderland, Mass: Sinauer Associates.
> On what page in Neidhardt did you find it? I wonder where I could have
> a mistake, because I based my estimations on my own experience with other
> bacteria of similar size to E.coli, but spherical. As far as I remember,
> 10^9 dry cells from a liter of culture weighed in the range of 1g pretty
> consistently for me about 6 years ago :-).
> >
> > Would you like the mailing address for that egg?
> No I have the book.
> >
> > Incidentally, who said that the largest viruses are larger than the
> smallest
> > bacteria?  I have to admit, I know little about viruses, but I can
> > believe that statement is true.  What virus is as large as a bacterium?
> Pox virus is 0.25 x 0.5 micron...
> - Emir

More information about the Microbio mailing list