"Vestitas" <vestitas at aol.com> wrote in message
news:20031015041824.15363.00000513 at mb-m23.aol.com...
> i've noticed that most bacterial ODs are measured at 600nm this being a
> wavelength at which the light is scattered and not absorbed by the cells
(?)
> therefore the higher the OD the more turbid the culture. So why do some
people
> measure OD at 660nm? - Please help, I'm confused
It does not generally matter for E.coli, 550, 600, or 660 nm. Cells of this
bacterium, as well as of most other bacteria, do not absorb much in this
area. However, one shouold be aware that overexpression of some proteins
might affect absorption spectra of the culture. It is always better checking
the 400-800nm spectrum of the particular culture you are using and selecting
the wavelength in the "pit" area where the absorbance stays unchanged in at
least the +-20nm range.
-Emir
