Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, Kobe 657-8501, Japan.
Appl Microbiol Biotechnol. 2012 Jun;94(6):1585-92. doi: 10.1007/s00253-012-3914-6. Epub 2012 Mar 10.
To improve the ability of recombinant Saccharomyces cerevisiae strains to utilize the hemicellulose components of lignocellulosic feedstocks, the efficiency of xylose conversion to ethanol needs to be increased. In the present study, xylose-fermenting, haploid, yeast cells of the opposite mating type were hybridized to produce a diploid strain harboring two sets of xylose-assimilating genes encoding xylose reductase, xylitol dehydrogenase, and xylulokinase. The hybrid strain MN8140XX showed a 1.3- and 1.9-fold improvement in ethanol production compared to its parent strains MT8-1X405 and NBRC1440X, respectively. The rate of xylose consumption and ethanol production was also improved by the hybridization. This study revealed that the resulting improvements in fermentation ability arose due to chromosome doubling as well as the increase in the copy number of xylose assimilation genes. Moreover, compared to the parent strain, the MN8140XX strain exhibited higher ethanol production under elevated temperatures (38 °C) and acidic conditions (pH 3.8). Thus, the simple hybridization technique facilitated an increase in the xylose fermentation activity.
为了提高重组酿酒酵母菌株利用木质纤维素饲料原料中半纤维素成分的能力，需要提高木糖转化为乙醇的效率。在本研究中，通过杂交产生了具有两套木糖同化基因的二倍体酵母菌株，这些基因编码木糖还原酶、木酮糖脱氢酶和木酮糖激酶。与亲本菌株 MT8-1X405 和 NBRC1440X 相比，杂种 MN8140XX 菌株在乙醇产量上分别提高了 1.3 倍和 1.9 倍。杂交也提高了木糖的消耗和乙醇的生产速率。本研究表明，发酵能力的提高是由于染色体加倍以及木糖同化基因拷贝数的增加所致。此外，与亲本菌株相比，MN8140XX 菌株在高温（38°C）和酸性条件（pH 3.8）下表现出更高的乙醇产量。因此，简单的杂交技术促进了木糖发酵活性的提高。
