Substrate Inhibition Growth Kinetics for Cutinase Producing Pseudomonas cepacia Using Tomato-peel Extracted Cutin

K. Dutta, V. Venkata Dasu, B. Mahanty and A. Anand Prabhu

Abstract
Using tomato-peel extracted cutin, an economically viable substrate, cutinase production by Pseudomonas cepacia was studied at different initial substrate concentrations (2–20 g L–1). The highest volumetric enzyme activity was observed at 10 g L–1 of cutin, which was inhibited at further higher concentrations. Various 3-, 4- and 5- parametric Monod-variant models were chosen to analyze the inhibition kinetics. The model parameters as well as goodness of fit were estimated using non-linear regression analysis. The 4- parameter Webb model was the best-fit model (R2 = 0.933), followed by the 3-parameter Andrews model (R2 = 0.92). Parameter sensitivity analysis revealed that the maximum specific growth rate was the most sensitive parameter for both the models, and the Webb constant was the least sensitive. Finally, based on a strong evidence ratio 190.65 from Akaike’s information content criteria analysis as well as extra sum of square F test (P > 0.05), it was found that 3-parameter Andrews model gave the best fit.

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Keywords
Cutinase, Pseudomonas cepacia, substrate inhibition model, Akaike’s information content criteria, parameter sensitivity