Use of continuous lactose fermentation for ethanol production by Kluveromyces marxianus for verification and extension of a biochemically structured model

摘要

A biochemically structured model has been developed to describe the continuous fermentation of lactose to ethanol by Kluveromyces marxianus and allowed metabolic coefficients to be determined. Anaerobic lactose-limited chemostat fermentations at different dilution rates (0.02-0.35h~(-1)) were performed. Species specific rates of consumption/formation, as well as yield coefficients were determined. Ethanol yield (0.655 C-mol ethanol*C-mol lactose~(-1)) was as high as 98% of theoretical. The modeling procedure allowed calculation of maintenance coefficients for lactose consumption and ethanol production of m_s=0.6029 and m_e=0.4218 (C-mol) and (C-molh)~(-1), respectively. True yield coefficients for biomass, ethanol and glycerol production were calculated to be Y~(true) _(sx)=0.114, Y~(true) _(ex)=0.192 and Y_(sg)=2.250 (C-mol) and (C-mol)~(-1), respectively. Model calculated maintenance and true yield coefficients agreed very closely with those determined by regressions of the experimental data. The model developed provides a solid basis for the rational design of optimised fermentation of cheese whey.