Semicontinuous culture

Douglas B. Kell dbk at aber.ac.uk
Fri Aug 28 17:40:10 EST 1998

Dennis Bayrock wrote in message ...


>    I would like to continue this discussion to hear of any different
>"modes" or descriptions of fermentation you have come across in your
>                                                    Dennis Bayrock

What Yarlipo described (grow a batch culture, take out most of the grown
culture, chuck in fresh medium and grow it up again, repeat ad lib) is
classically called 'fill and draw' culture. A somewhat different and
relatively novel variant in which the medium is not all added in one go (so
it is a modified fed batch) has been popularised by Mike Bushell at Surrey
Univ and is called by him Cyclic Fed Batch Culture.

John Pirt in the late 1970s used square waves in "continuous" cultures,
which had some advantages [and Jay Bailey used sinusoidal inputs in chemical
reactors; ditto].

Re 'turbidostats', there are many ways of controlling the biomass of a
cultures besides turbitity (OD); we have used the dielectric permittivity,
which allows much higher biomass levels to be set  (Markx, G.H., Davey, C.L.
& Kell, D.B. (1991) The permittistat: a novel type of turbidostat. J. Gen.
Microbiol., 137, 735-743) and thereby discovered the first experimental
example of deterministic chaos in the growth rate of a culture (Davey, H.M.,
Davey, C.L., Woodward, A.M., Edmonds, A.N., Lee, A.W. & Kell, D.B. (1996)
Oscillatory, stochastic and chaotic growth rate fluctuations in
permittistatically-controlled yeast cultures. Biosystems 39, 43-61).

I don't read newsgroups much, so if there is follow-up perhaps it could be
cc'd to me by email.

(Prof.) Douglas B. Kell, Cledwyn Building,
Institute of Biological Sciences, University of Wales,
Aberystwyth SY23 3DD
Tel: +44 1970 622334   Fax: +44 1970 622354
dbk at aber.ac.uk

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