# mass of bacteria

Nicholas Landau njl2q at virginia.edu
Mon Apr 8 23:57:13 EST 2002

```The largest viruses are bigger than bacteria?  Which virus?  I never heard
that (but then, I never studied virology).

--Nick

Graham Shepherd wrote:

> Smarty <smartman at comcast.net> wrote in message
> news:3cab7bd6.18969629 at news.in.comcast.giganews.com...
> > Less than 500 milligrams
> >
>
>
> You can get an approximation by calculating the volume of the organism from
> typical dimensions (eg for E.coli assume it's a cylinder 1 micron long with
> a diameter of 0.5 micron) and assume that the density is the same as water.
> (It is greater, otherwise you couldn't spin them down - but it's probably
> not much greater. You could determine the density on a gradient if it's
> critical).
>
> A rough calculation indicates that the volume is about 0.2 cubic microns.
> That's 5,000,000,000 per cubic millimeter, or 5,000,000,000,000 per cubic
> cm. Assuming 1 gram per cubic cm, one bacterium weighs about 0.2 picogram.
>
> Viruses are much more variable in size than bacteria (the biggest viruses
> are bigger than the smallest bacteria). But you could do the same
> calculation for a specific virus.
>
> GS

```