INHIBITORY NUTRIENTS

Analysis of growth rate expressions

Overview:

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.

Introduction:

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.

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Reference:

H. R. Bungay, "Growth rate expressions for two substrates one of which is inhibitory", Jour. Biotechnol. 34: 97-100 (1994)
Last update: 10-Oct-94