Fermentation of the pentose sugar xylose to produce ethanol using lignocellulosic biomass would make bioethanol production economically more competitive. Sac- charomyce cerevisise, an efficient ethanol producer, canno...Fermentation of the pentose sugar xylose to produce ethanol using lignocellulosic biomass would make bioethanol production economically more competitive. Sac- charomyce cerevisise, an efficient ethanol producer, cannot utilize xylose because it lacks the ability to convert xylose to its isomer xylulose. In this study, XYLA gene encoding xylose isomerase (XI) from Thermoanaerobacter tengcongensis MB4T and XKS1 gene encoding xylulokinase (XK) from Pichia stipitis were cloned and functionally coexpressed in Saccharomyces cerevisiae EF-326 to construct a recombinant xylose-utilizing strain. The resulting strain S. cerevisiae EF 1014 not only grew on xylose as sole carbon source, but also produced ethanol under anaerobic conditions. Fermentations performed with different xylose concentrations at different temperatures demonstrated that the highest ethanol produc- tivity was 0.11 g/g xylose when xylose concentration was pro- vided at 50 g/L. Under this condition, 28.4% of xylose was consumed and 1.54 g/L xylitol was formed. An increasing fermentation temperature from 30℃ to 37℃ did not im- prove ethanol yield.展开更多
基金supported by the National Basic Research Program of China(No.2004CB719002)the National Knowledge Innovation Project from the Chinese Academy of Sciences
文摘Fermentation of the pentose sugar xylose to produce ethanol using lignocellulosic biomass would make bioethanol production economically more competitive. Sac- charomyce cerevisise, an efficient ethanol producer, cannot utilize xylose because it lacks the ability to convert xylose to its isomer xylulose. In this study, XYLA gene encoding xylose isomerase (XI) from Thermoanaerobacter tengcongensis MB4T and XKS1 gene encoding xylulokinase (XK) from Pichia stipitis were cloned and functionally coexpressed in Saccharomyces cerevisiae EF-326 to construct a recombinant xylose-utilizing strain. The resulting strain S. cerevisiae EF 1014 not only grew on xylose as sole carbon source, but also produced ethanol under anaerobic conditions. Fermentations performed with different xylose concentrations at different temperatures demonstrated that the highest ethanol produc- tivity was 0.11 g/g xylose when xylose concentration was pro- vided at 50 g/L. Under this condition, 28.4% of xylose was consumed and 1.54 g/L xylitol was formed. An increasing fermentation temperature from 30℃ to 37℃ did not im- prove ethanol yield.
