两株高糖分利用能力的酿酒酵母呼吸突变体选育

Breeding of Two Respiration-impaired Mutants of Saccharomyces cerevisiae with Enhanced Sugar Metabolism Capacity

以酿酒酵母乙醇发酵高产工业菌株MF1002为始发菌株,对其营养细胞进紫外线诱变,筛选得到两株性状稳定的呼吸缺陷型突变体MF15c和MF11a。菌体细胞对2,3,5-氯化三苯四氮唑(TTC)显色测定呼吸强度的结果表明,两突变菌株的相对呼吸强度分别只有始发菌株的57.77%和47.25%。与现有报道的呼吸缺陷突变体不同,两株突变体的细胞生长速率只在培养初期略低于始发菌株,总体生长速率与始发菌株几乎没有差异,在YPD平板上培养也不形成小菌落。比较蔗糖发酵试验表明,两株突变体的乙醇产量较始发菌株只分别略提高6.48%-6.59%(MF15c)和1.66%-1.97%(MF11a),但发酵终止的残总糖含量却显著低于始发菌株,分别减少34.85%和19.70%,发酵效率较始发菌株分别显著提高6.69%和4.71%,表明这两株突变体为新型的呼吸缺陷型突变。鉴于提高乙醇发酵的发酵效率可显著降低生产成本,认为这两株突变菌株具有较高的潜在工业利用价值。

Two phenotype stable respiration-impaired mutants, named as MF15c and MF1 la, were selected by UV-ray inducing a high- ethanol-producing industrial strain MFIO02 of Saccharomyces cerevisiae. The relative respiration rate of mutants, determined through analysis of colorimetric reaction of 2, 3, 5-triphenyl tetrazolium chloride （ TTC ） in the ceils, was only 57.77% and 47.25% of MFIO02, respectively. Unlike the most previously reported mutation, both mutants were with the novel phenotypes that the growth rate was not significanly different from the parent strain, and no ＂petite colonie＂ were observed on YPD plate cultivation. However, the fermentation with sucrose as substrate showed that, comparing with MFIO02, the ethanol yield of mutants were only slightly enhanced 6.48%-6.59% （ MF15c ） and 1.66%-1.97% （ MFI la ） , but the content of total residual sugar of mutants were significantly decreased 34.85% （ MF15c ） and 19.70% （ MF1 la ） , the fermentation efficiency of mutants were also significantly enhanced 6.69% and 4.71%, respectively, indicating MF15c and MF1 l a were novel respiration- impaired mutants. Since enhancing the fermentation efficiency involves a significant benefit for ethanol fermentation, we argue that both mutants have a greal p^tential utilization value for ethanol production.