Analysis of growth rate expressions
Growth rate is fundamental to all bioprocessing with living cells. A key
concept is growth-limiting nutrient,
the one in lowest proportion to the others. It will be exhausted first
and is the focus for growth rate control. When limitation can shift from
one nutrient to another, the equations relating specific growth rate coefficient
become more complicated. If one nutrient is inhibitory to growth as its
concentration rises, additional terms are needed in these equations.
Natural nutrients are seldom pure. Compounds or mixtures of compounds contain
carbon, hydrogen, nitrogen, and other elements in various proportions and
may supply precursors at several locations in metabolic pathways. Very
seldom is an unreacted element taken up by cells; they prefer pre-formed
groups. A rigorous treatment of growth rate control should consider the
exact biochemical compositions of all nutrients, but this is impractical.
We simplify the complicated patterns of nutrition by speaking of the "carbonaceous
ingredient", the "nitrogeneous ingredient", and the like.
Select any of the following:
H. R. Bungay, "Growth rate expressions for two substrates one of which
is inhibitory", Jour. Biotechnol. 34: 97-100 (1994)
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