Persistant phenotypic differences (serial subculture)?

Guenter Jost Guenter.Jost at io-warnemuende.de
Thu Jun 6 05:20:42 EST 1996

In article <graham.833991946 at biodec.wustl.edu>, graham at biodec.wustl.edu 
>While certainly amplification of specific subpopulations holding a 
>competitive advantage may be involved in these effects, I am wondering 
>if typical mutation rate of say 10(-6)/generations would be sufficient
>to overtake of batch culture growing a rich broth from an incoculum of 
>say 1%. This would only represent some 6-8 generations in most cases.
>Subsequent re-subculturings might lead to more of this type of clonal 
>amplificiation, but I'm not sure if it would be the major cause of 
>such effects with the first or even second or third subculture.
>Anyone have a better idea of the mathematics of "attentuation"?
>Please continue,
>J. Graham PhD 
>Biology Department 
>Washington University of St. Louis 
I would also think that it could be connected with mutation events. 
Decades ago I remember a discussion on a conference about such a problem.
The outcome was like that after a long run of a chemostate (several tenth 
of generations) there should be a remarkable difference between the last
culture and the inoculum. The pessimists should stop work with 
chemostates if they use it in a manner to produce an "equal product" for
their research needs. The optimists argue that you could always identify
e.g. E.coli as E.coli during the chemostate run.
At least the differences caused by different dilutions suggest a solution
within the direction of mutation to me.

Günter Jost
Baltic Sea research institute
Guenter.Jost at io-warnemuende.de

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