Kinetic Modeling of Ethanol Production by Scheffersomyces stipitis from Xylose.

School of Food Engineering, University of Campinas, CEP 13083-862, Campinas, SP, Brazil, .
Applied biochemistry and biotechnology (Impact Factor: 1.94). 10/2013; DOI: 10.1007/s12010-013-0546-y
Source: PubMed

ABSTRACT This work focuses on the kinetics of ethanol production by Scheffersomyces stipitis on xylose with the development of a mathematical model considering the effect of substrate and product concentrations on growth rate. Experiments were carried out in batch and continuous modes, with substrate concentration varying from 7.2 to 145 g L(-1). Inhibitory effects on cell growth, substrate uptake, and ethanol production rates were found to be considerable. Kinetic parameters were obtained through linear and non-linear regression methods. Experiments in continuous mode were performed at different dilution rates to evaluate the inhibitory effect of ethanol. A mixed mathematical model which combined Andrews and Levenspiel's models, combining substrate and product inhibition, was used. A quasi-Newton routine was applied to obtain a more accurate fitting of kinetic parameters. The parameters such as cell to product factor (Y P/X) and limiting cell yield (Y X) were shown to be dependent on substrate concentration. The kinetic model fitted satisfactorily the experimental data.

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