Genetic improvement of xylose metabolism by enhancing the expression of pentose phosphate pathway genes in Saccharomyces cerevisiae IR-2 for high-temperature ethanol production

• Published in: Journal of industrial microbiology & biotechnology 2017-06, Vol.44 (6), p.879-891
• Main Authors: Kobayashi, Yosuke, Sahara, Takehiko, Suzuki, Toshihiro, Kamachi, Saori, Matsushika, Akinori, Hoshino, Tamotsu, Ohgiya, Satoru, Kamagata, Yoichi, Fujimori, Kazuhiro E.
• Format: Article
• Language: English
• Subjects: Biochemistry; Bioinformatics; Biomedical and Life Sciences; Biotechnology; Cell Culture and Bioengineering - Original Paper; Cellulase; Cellulase - metabolism; Combinatorial analysis; Ethanol; Ethanol - metabolism; Fermentation; Genes; Genetic Engineering; High temperature; Hot Temperature; Hydrolysis; Inorganic Chemistry; Kluyveromyces - genetics; Life Sciences; Lignin - metabolism; Lignocellulose; Metabolism; Microbiology; Overexpression; Pentose; Pentose phosphate pathway; Pentose Phosphate Pathway - genetics; Saccharification; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Temperature; Temperature effects; Transaldolase - genetics; Transketolase - genetics; Xylose; Xylose - metabolism; Yeast; Yeasts
• ISSN: 1367-5435; 1476-5535
• DOI: 10.1007/s10295-017-1912-5

The pentose phosphate pathway (PPP) plays an important role in the efficiency of xylose fermentation during cellulosic ethanol production. In simultaneous saccharification and co-fermentation (SSCF), the optimal temperature for cellulase hydrolysis of lignocellulose is much higher than that of fermentation. Successful use of SSCF requires optimization of the expression of PPP genes at elevated temperatures. This study examined the combinatorial expression of PPP genes at high temperature. The results revealed that over-expression of TAL1 and TKL1 in Saccharomyces cerevisiae ( S. cerevisiae ) at 30 °C and over-expression of all PPP genes at 36 °C resulted in the highest ethanol productivities. Furthermore, combinatorial over-expression of PPP genes derived from S. cerevisiae and a thermostable yeast Kluyveromyces marxianus allowed the strain to ferment xylose with ethanol productivity of 0.51 g/L/h, even at 38 °C. These results clearly demonstrate that xylose metabolism can be improved by the utilization of appropriate combinations of thermostable PPP genes in high-temperature production of ethanol.