Sonderegger Marco, Jeppsson Marie, Larsson Christer, Gorwa-Grauslund Marie-Françoise, Boles Eckhard, Olsson Lisbeth, Spencer-Martins Isabel, Hahn-Hägerdal Bärbel, Sauer Uwe
Institute of Biotechnology, ETH Zürich, CH-8093 Zürich, Switzerland.
Biotechnol Bioeng. 2004 Jul 5;87(1):90-8. doi: 10.1002/bit.20094.
Lignocellulose hydrolysate is an abundant substrate for bioethanol production. The ideal microorganism for such a fermentation process should combine rapid and efficient conversion of the available carbon sources to ethanol with high tolerance to ethanol and to inhibitory components in the hydrolysate. A particular biological problem are the pentoses, which are not naturally metabolized by the main industrial ethanol producer Saccharomyces cerevisiae. Several recombinant, mutated, and evolved xylose fermenting S. cerevisiae strains have been developed recently. We compare here the fermentation performance and robustness of eight recombinant strains and two evolved populations on glucose/xylose mixtures in defined and lignocellulose hydrolysate-containing medium. Generally, the polyploid industrial strains depleted xylose faster and were more resistant to the hydrolysate than the laboratory strains. The industrial strains accumulated, however, up to 30% more xylitol and therefore produced less ethanol than the haploid strains. The three most attractive strains were the mutated and selected, extremely rapid xylose consumer TMB3400, the evolved C5 strain with the highest achieved ethanol titer, and the engineered industrial F12 strain with by far the highest robustness to the lignocellulosic hydrolysate.
木质纤维素水解产物是用于生物乙醇生产的丰富底物。对于这样的发酵过程而言,理想的微生物应具备将可用碳源快速高效地转化为乙醇的能力,同时对乙醇以及水解产物中的抑制成分具有高耐受性。一个特殊的生物学问题是戊糖,主要的工业乙醇生产菌酿酒酵母不能天然代谢戊糖。最近已经开发出了几种重组、突变和进化的木糖发酵酿酒酵母菌株。在此,我们比较了8种重组菌株和2个进化群体在限定培养基以及含木质纤维素水解产物的培养基中的葡萄糖/木糖混合物上的发酵性能和稳健性。一般来说,多倍体工业菌株比实验室菌株消耗木糖的速度更快,并且对水解产物的耐受性更强。然而,工业菌株积累的木糖醇比单倍体菌株多30%,因此产生的乙醇比单倍体菌株少。最具吸引力的三种菌株分别是经过突变和筛选的、消耗木糖极快的TMB3400,乙醇产量最高的进化C5菌株,以及对木质纤维素水解产物耐受性最强的工程化工业F12菌株。