Monod kinetics substrate inhibition

The Monod kinetic parametos were evaluated by least squares fitting procedures, for tiie single and multiple substrate systems with/without mutual inhibition, and were indicated in Table 1 [6]. The value of indicates the linear decomposition rate. It is dear that the decomposition rate for prc iionic acid is significantly lower than those for acetic add and butyric acid. 

Respiration inhibition kinetics analysis (RIKA) involves the measurement of the effect of toxicants on the kinetics of biogenic substrate (e.g., butyric acid) removal by activated sludge microorganisms. The kinetic parameters studied are max> the maximum specific substrate removal rate (determined indirectly by measuring the maximum respiration rate), and Ks, the half-saturation coefficient [19]. The procedure consists of measuring with a respirometer the Monod kinetic parameters, Vinax and Ks, in the absence and in the presence of various concentrations of the inhibitory compound. 

The shape of the performance curve for a continuous stirred-tank fermenter is dependent on the kinetic behaviour of the micro-organism used. In the case where the specific growth rate is described by the Monod kinetic equation, then the productivity versus dilution rate curve is given by equation 5.137 and has the general shape shown by the curve in Fig. 5.58. However, if the specific growth rate follows substrate inhibition kinetics and equation 5.65 is applicable then, at steady state, equation 5.131 becomes ... 

The growth rate for cells in a bioreactor can follow a variety of growth equations. Monod kinetics is represented by part (1) of Problem 8.3. A substrate-inhibition growth rate is given by (see Shuler, 1988) ... 

Figure 5.17. Diagram of the mathematical model describing the relationship between the specific growth rate jx (or specific rate of substrate utilization, q ) and the limiting substrate concentration s (A. Moser, 1978b) 1, Monod kinetics 2, Monod with S inhibition 3, Monod with S inhibition at high X 4, as 3 with P inhibition 5, as 4 with endogenous metabolism 6, as 4 with sequential metabolism of two substrates, that is, biosorption and 7, transients such as lag phase.

It is reasonable to assume that /x does not depend on V and F, so only functional relations between p,k k and Xk k and 5, are estimated, giving the results shown in Figure 2. These plots indicate that p,k k does not depend on Xk k, but is highly dependent on 5 1, which in turn suggests to replace the assumption of constant fj, with an assumption of /x being a function of S that complies with the revealed functional relation. To a skilled biotechnologist this relation is a clear indication of Monod kinetics and substrate inhibition and immediately suggests to replace /x with the true function /x(5) in (7). 

Specific detail on Michaelis-Menten kinetics, quasi steady-state approximations, competitive and non-competitive inhibitions, substrate inhibition, rate expressions for enzyme catalysis and deactivations, Monod growth kinetics, etc. are not presented in an extensive manner although additional information is available in the work of Vasudevan for the interested leader. " Also note that the notation adopted by Vasudevan is employed throughout this chapter. 

Han, K., Levenspiel, O., 1988. Extended Monod kinetics for substrate, product, and cell inhibition. Biotechnology and Bioengineering 32, 430—437. 

Because of the failure of the Monod equation to find universal applicability, many researchers have suggested variations on the form of this equation in attempts to better characterize the kinetic behavior of substrate-limited growth of microorganisms. There are several more complex mathematical models that take into account not only inhibition by substrates and/or products of biochemical reactions, but also other factors, such as cell death and cell maintenance effects and multiple limiting substrates (5,6). 

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