Kinetic Analysis of Microbial Interactions

The behavior and mathematical model of a mixed population are basically similar to those of a pure culture. The Monod model can often be used as 

1 Competition (Between Two Organisms Growing on a Single Substrate) 

With the simplest model including two species (x, X2) competing for the same limiting substrate (s), the principle of selection can be demonstrated ( survival of the fittest —organism with the greater specific growth rate). The scheme can be written 

The kinetic model, using the Monod equation for = f s), will be for a CSTR 

The principle factors governing the kinetic behavior are the differences in pi and Ks of both species, for example, mutants at different dilution rates. The dependencies pi s) can be divided into two main categories. The first type (cases I, II, IV, V in Fig. 5.57) is characterized by the fact that the in s) curves for both mutants have no common point apart from the origin. In the second type (cases III, VI), the two curves intersect (see Fig. 5.57). It is clear that the curves will cross each other if 2 / max, 1 and K 2 si All of these cases are illustrated in Fig. 5.58, where correspondingly denoted areas reflect the magnitude of the ratios jUniax,i// max,2 and Ksi/Ks2 (Sikyta et al., 1979). Thus, 

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