纤维素乙醇生产重组酿酒酵母菌株的构建与优化研究进展

Progress of research on construction and optimization of recombinant Saccharomyces cerevisiae strains for cellulosic ethanol production

寻找化石能源的替代品以及开发和利用生物能源已引起国内外研究者的广泛关注。提高酿酒酵母利用来源广泛、贮存丰富的农林废弃物等木质纤维素原料生产燃料乙醇的效率是生物能源的重要研究内容,但是,重组酿酒酵母木糖发酵性能低是限制纤维素乙醇经济性的关键问题。本文总结了酿酒酵母中木糖代谢途径的构建和优化以及木糖转运对木糖利用的影响,分析了重组酵母利用纤维素水解液进行乙醇发酵的研究现状,并对进一步提高重组酿酒酵母纤维素乙醇生产效率的研究趋势进行了展望。目前国内外已经构建了可有效利用木糖产乙醇的重组酵母,但对其木糖代谢机制的研究还尚未深入,限制了重组菌株的定向改造。此外,目前缺少在纤维素生物质水解液发酵实际应用过程中对重组菌株的评价。因此,加强重组酵母菌株对木糖利用相关代谢调控机理的分析,注重多种抑制物对菌株发酵性能的影响,结合真实底物纤维素乙醇发酵过程进行重组菌株的构建和优化,从而进一步提高纤维素乙醇生产的经济性,是未来菌株构建的重要研究方向。

The increasing challenges on gradual depletion of fossil fuel and global warming are driving the development of alternative fuels and utilization of bioenergy. Production of fuel ethanol from lignocellulosic feedstocks including a variety of agricultural and forestry residues has received increasing interests in recent years. Saccharomyces cerevisiae is the most commonly used microbial organism for ethanol production. However, it cannot efficiently assimilate xylose, which is the most abundant pentose in lignocellulosic hydrolysates. Therefore, construction and optimization of xylose utilizing S. cerevisiae is of great importance for improving economic cellulosic ethanol production. The construction and optimization of recombinant S. cerevisiae strains by integrating xylose utilization pathway, and the effect of xylose transport on xylose assimilation were summarized. Furthermore, the current status of cellulosic ethanol production using the recombinant S. cerevisiae strains was discussed, and further prospects on improvement of production efficiency of cellulosic ethanol was provided. Currently, the yield of ethanol from xylose by the recombinant strains has been improved significantly.However, the regulatory mechanisms of xylose metabolism remain unclear, which limits further optimization of production efficiency. In addition, the evaluation of fermentation performance of the recombinant strains using various lignocellulosic hydrolysates is limited. Future studies will be focused on the regulation of xylose metabolism in the recombinant strains, and the influence of various inhibitors in the hydrolysates on fermentation performance will be emphasized. Strain optimization will be further explored in combination with different fermentation processes, and economic production of celluosic ethanol using the efficient recombinant stain is expected to be achieved.