Department of Biotechnology, Pukyong National University, Busan, 48513, South Korea.
Department of Food Science and Biotechnology, Kyungpook National University, Daegu, 37224, South Korea.
Bioprocess Biosyst Eng. 2019 Sep;42(9):1421-1433. doi: 10.1007/s00449-019-02139-0. Epub 2019 May 4.
A total monosaccharide concentration of 47.0 g/L from 12% (w/v) Gracilaria verrucosa was obtained by hyper thermal acid hydrolysis with 0.2 M HCl at 140°C for 15 min and enzymatic saccharification with CTec2. To improve galactose utilization, we overexpressed two genes, SNR84 and PGM2, in a Saccharomyces cerevisiae CEN-PK2 using CRISPR/Cas-9. The overexpression of both SNR84 and PGM2 improved galactose utilization and ethanol production compared to the overexpression of each gene alone. The overexpression of both SNR84 and PGM2 and of PGM2 and SNR84 singly in S. cerevisiae CEN-PK2 Cas9 produced 20.0, 18.5, and 16.5 g/L ethanol with ethanol yield (Y) values of 0.43, 0.39, and 0.35, respectively. However, S. cerevisiae CEN-PK2 adapted to high concentration of galactose consumed galactose completely and produced 22.0 g/L ethanol at a Y value of 0.47. The overexpression of both SNR84 and PGM2 increased the transcriptional levels of GAL and regulatory genes; however, the transcriptional levels of these genes were lower than those in S. cerevisiae adapted to high galactose concentrations.
从 12%（w/v）的石花菜中获得了 47.0 g/L 的总单糖浓度，采用 0.2 M HCl 在 140°C 下进行超热酸水解 15 分钟，并使用 CTec2 进行酶解。为了提高半乳糖的利用率，我们使用 CRISPR/Cas-9 在酿酒酵母 CEN-PK2 中过表达了两个基因 SNR84 和 PGM2。与单独过表达每个基因相比，过表达 SNR84 和 PGM2 都提高了半乳糖的利用率和乙醇的产量。在酿酒酵母 CEN-PK2 Cas9 中过表达 SNR84 和 PGM2 以及 PGM2 和 SNR84 分别产生了 20.0、18.5 和 16.5 g/L 的乙醇，乙醇产率（Y）值分别为 0.43、0.39 和 0.35。然而，适应高浓度半乳糖的酿酒酵母 CEN-PK2 完全消耗了半乳糖，并以 0.47 的 Y 值生产了 22.0 g/L 的乙醇。过表达 SNR84 和 PGM2 增加了 GAL 和调控基因的转录水平；然而，这些基因的转录水平低于适应高半乳糖浓度的酿酒酵母。
