| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 31624 | Metabolic Engineering | 2012 | 10 Pages |
Effective conversion of xylose in lignocelluloses is expected to reduce the production cost of second-generation biofuels significantly. The factors affecting xylose fermentation in Saccharomyces cerevisiae that express xylose reductase–xylitol dehydrogenase (XR–XDH) are studied. Although overproduction of non-oxidative pentose phosphate pathway significantly increased the aerobic-specific growth rate on xylose and slightly improved conversion of xylose to ethanol under oxygen-limited conditions, the elimination of respiration by deleting cytochrome C oxidase subunit IV gene impeded aerobic growth on xylose. However, the adaptive evolution of the respiratory-deficient strain with an NADP+-preferring XDH mutant in xylose media dramatically improved its xylose-fermenting ability. The specific growth rate, ethanol yield, and xylitol yield of the evolved strain on xylose were 0.06 h−1, 0.39 g g−1, and 0.13 g g−1 consumed xylose, respectively. Similar to anaerobic fermentation, the evolved strain exhibited accumulated ethanol rather than recycled it under aerobic conditions.
► Xylose pathway modifications and adaptive evolution were adopted in Saccharomyces cerevisiae. ► The overproduction of XK and PPP can increase the metabolic flux from xylose to ethanol. ► The respiration disruption strain lost growth ability on xylose. ► Adaptive evolution only can recover the growth of strain whose cofactors of XR and XDH couple better. ► The evolved strain accumulated ethanol rather than recycled whether anaerobic or aerobic.
