Plotting growth data

Forday Wayne Lee fwl at titan.np.ac.sg
Fri Sep 22 19:18:42 EST 1995

In article <43scau$35r at dopey.cc.utexas.edu>,
hantash <hantash at dopey.cc.utexas.edu> wrote:
:>Also remeber When taking ABs. readings that go beyond say 0.8 to dilute 
:>your culture
:>before taking the reading. This is because alot of people don't do this and
:>you end up seeing growth curves with a stationery phase (what ever
:>that phase may be) at Abs 1 when infact the culture is still
:>in the "exponential phase" !!
:>This is incorrect. As the cultre density rises, the ability of the spec to 
:>read light scattering is compromised. The machine can read through a 
:>certain range only. 
With Lactobacilli, I find an ABS of 0.5 too high. When you look at your
diluted culture swirl it. If you can see "clouds" of turbidity, then it is
too high.

In our lab, use volumetric glassware for our dilutions:


and so on.

The reason for this is that good Absorbance data is so hard to get, if
you do not do your dilutions accurately, then you do not get good results.

Wayne Lee Forday, Biotechnology Department 
Ngee Ann Polytechnic, Singapore 
fwl at np.ac.sg

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