An introduction to practical steady state kinetics

3 An introduction to practical steady state kinetics AppUcations of steady state kinetics 

Steady states or steady state approximations, are used to describe mechanisms and to solve equations for a great variety of phenomena such as 

The rate constant in this equation corresponds to 1/t, as derived in section 3.1. For a culture grown in an undisturbed medium the real growth curve would be S shaped. Such functions for growth curves and population limits in demographic or ecological systems have been developed on the basis of many different models and have already been referred to in section 1.1. 

We shall now describe a simple realistic model for the growth of cultures of microorganisms in a chemostat. The rate of replication of microorganisms depends on the concentration of nutrients in the medium. Let us assume, for simplicity, that the rate of growth is limited by one substrate. The response, R, of many systems to a concentration, cg, of a substrate can be described by 

For many practical purposes large scale bacterial production is carried out in a chemostat. This device, a further development of the method used by Novick Szilard (1950) and Monod (1950), allows continuous growth by constant removal of organisms and addition of nutrients, as well as the neutralization of inhibitory products, for instance by keeping pH constant. The design of the process is described by Herbert, Elsworth TeUing (1956) and a brief summary of the theory will be discussed as an example of steady state behaviour. 

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