Biomass Conversion Research Laboratory (BCRL), Department of Chemical Engineering and Materials Science, Michigan State University, University Corporate Research Complex, 3900 Collins Road, Lansing, MI 48910, USA.
Bioresour Technol. 2012 May;111:294-300. doi: 10.1016/j.biortech.2012.01.154. Epub 2012 Feb 8.
Reduced xylose fermentation performance has been an issue during fermentation of AFEX™ hydrolysate using Saccharomyces cerevisiae 424A (LNH-ST) or Escherichia coli KO11. To better understand why fermentation performance is reduced, we quantitatively studied the effects of compounds present in the fermentation broth on xylose consumption. The compounds include biomass degradation products, ethanol and fermentation metabolites. The xylose consumption capability of E. coli KO11 was almost totally inhibited by the presence of both degradation products and ethanol. On the other hand, for S. cerevisiae 424A, 89% reduction of xylose consumption rate was found during hydrolysate fermentation. Degradation products, ethanol and fermentation metabolites were responsible for 32%, 24% and 33% of such reduction, respectively. Those results suggest that to further improve the xylose fermentation in hydrolysate, strains should be selected not only for degradation products tolerance but also for ethanol and fermentation metabolites tolerance.
利用酿酒酵母 424A（LNH-ST）或大肠杆菌 KO11 发酵 AFEX™水解物时，木糖发酵性能降低一直是一个问题。为了更好地理解发酵性能降低的原因，我们定量研究了发酵液中存在的化合物对木糖消耗的影响。这些化合物包括生物量降解产物、乙醇和发酵代谢物。降解产物和乙醇的存在几乎完全抑制了大肠杆菌 KO11 的木糖消耗能力。另一方面，对于酿酒酵母 424A，在水解物发酵过程中，木糖消耗率降低了 89%。降解产物、乙醇和发酵代谢物分别导致了 32%、24%和 33%的降低。这些结果表明，为了进一步提高水解物中的木糖发酵，不仅应选择对降解产物耐受的菌株，还应选择对乙醇和发酵代谢物耐受的菌株。
