Department of Microbiology, University of Stellenbosch, Stellenbosch 7600, South Africa.
J Ind Microbiol Biotechnol. 2012 Oct;39(10):1445-52. doi: 10.1007/s10295-012-1150-9. Epub 2012 Jun 16.
Recombinant Saccharomyces cerevisiae strains expressing β-glucosidases from Thermoascus aurantiacus (Tabgl1) and Phanerochaete chrysosporium (PcbglB and Pccbgl1) were constructed and compared to S. cerevisiae Y294[SFI], previously identified as the best β-glucosidase-producing strain. The PcbglB was also intracellularly expressed in combination with the lac12 lactose permease of Kluyveromyces lactis in S. cerevisiae Y294[PcbglB + Lac12]. The recombinant extracellular β-glucosidases indicated maximum activity in the pH range 4-5 and temperature optima varying from 50 to 75 °C. The S. cerevisiae Y294[Pccbgl1] strain performed best under aerobic and anaerobic conditions, producing 2.6 times more β-glucosidase activity than S. cerevisiae Y294[SFI] and an ethanol concentration of 4.8 g l(-1) after 24 h of cultivation on cellobiose as sole carbohydrate source. S. cerevisiae Y294[Tabgl1] was unable to grow on cellobiose (liquid medium), whereas S. cerevisiae Y294[PcbglB + Lac12] exhibited limited growth.
构建了表达来自嗜热曲霉（Tabgl1）和黄孢原毛平革菌（PcbglB 和 Pccbgl1）β-葡萄糖苷酶的重组酿酒酵母菌株，并与先前鉴定为产β-葡萄糖苷酶最佳菌株的酿酒酵母 Y294[SFI]进行了比较。还将 PcbglB 与乳糖渗透酶 Lac12 一起在酿酒酵母 Y294[PcbglB + Lac12]中进行了细胞内表达。重组的细胞外β-葡萄糖苷酶在 pH 值为 4-5 范围内和温度最佳范围从 50 到 75°C 时表现出最大的活性。在有氧和厌氧条件下，酿酒酵母 Y294[Pccbgl1]菌株表现最佳，在以纤维二糖为唯一碳源培养 24 小时后，产生的β-葡萄糖苷酶活性比酿酒酵母 Y294[SFI]高 2.6 倍，乙醇浓度为 4.8 g l(-1)。酿酒酵母 Y294[Tabgl1]无法在纤维二糖（液体培养基）上生长，而酿酒酵母 Y294[PcbglB + Lac12]的生长则受到限制。
