絮凝酿酒酵母的构建及其发酵特性

Construction of a flocculating yeast for fuel ethanol production

把S.cerevisiae W303-1A的絮凝基因FLO1和G418抗性基因kanMX接入质粒pYX212,构建重组质粒pYX-FLO-kan并转化S.cerevisiae Z WA46,得到了较强絮凝能力且传代稳定的重组菌ZWA46-F2。考察其絮凝能力及发酵特性,实验结果表明:该重组菌在生长稳定期前期启动絮凝,与葡萄糖的耗竭非耦联;在初始pH2.5～6.0范围内絮凝值无明显改变;乙醇产量最高达到8.6%(体积),乙醇对葡萄糖的转化率达到其理论转化率的89.8%。重组菌ZWA46-F2良好的絮凝性能有利于从发酵液中分离细胞和细胞回用,在燃料乙醇工业生产中有一定的应用价值。

The expression vector pYX212 harboring the flocculation gene FLO1 from S. cerevisiae W303- 1A and the G418 resistance gene kanMX was transformed into S. cerevisiae ZWA46. The transformant ZWA46-F2 was obtained and showed strong and stable flocculation ability. Other properties of the recombinant strain were also studied. The results demonstrated that the onset flocculation was in the early stationary phase, not coincident with glucose depletion in the culture medium. Moreover, the flocculation ability of the transformant showed no difference at initial pH ranging from 2.5 to 6.0, and could achieve the maximum ethanol concentration of 8. 6% （vol.） with an ethanol yield on glucose of 89. 8% of the theoretical value. The flocculation property of the transformant ZWA46-F2 seemed to have potential application in the fuel ethanol industry due to the easiness to separate and reuse yeast cells.