Biodegradation characterisation and kinetics of m-cresol by Lysinibacillus cresolivorans

Abstract

Because of the substrate inhibition on the cell growth, Haldane’s equation was selected due to its wide applicability for assessing the growth kinetics of inhibitory substrate (Haldane, 1965): (2) where: Sis the substrate concentration (mg·ℓ-1), μmax is the maximum growth rate (h-1), KS is the substrate saturation coefficient and Ki is the substrate inhibition coefficient. The values of the parameters: µ max = 0.89 h-1, Ks = 426.25 mg∙ℓ-1, Ki = 51.26 mg∙ℓ-1, were derived using a nonlinear leastsquares regression analysis of ORIGIN 7.5 based on the experimental data obtained in the tests. The value of the squared 2-norm of the residual at these parameters was very small (3.0 × 10-4), which indicated that the regression curve agreed with the data very well. It could be seen in Fig. 7 that the maximum specific growth rate occurred at very low m-cresol concentrations. When the initial concentration of m-cresol was 151.5 mg·ℓ-1, the maximum specific growth rates were 0.1316 h-1.

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