Saliola M, Bellardi S, Marta I, Falcone C
Department of Cell and Developmental Biology, University of Rome La Sapienza, Italy.
Yeast. 1994 Sep;10(9):1133-40. doi: 10.1002/yea.320100902.
Four genes coding for alcohol dehydrogenase (ADH) activities were identified in Kluyveromyces lactis. Due to the presence in this yeast of multiple ADH isozymes, mutants in the individual genes constructed by gene replacement yielded no clear phenotype. We crossed these mutants and developed a screening procedure which allowed us to identify strains lacking several ADH activities. The analysis of the adh triple mutants revealed that each activity confers to the cell the ability to grow on ethanol as the sole carbon source. On the contrary, adh null strains failed to grow on this substrate, indicating that no other important ADH activities are present in K. lactis cells. In the adh null mutants we also found a residual production of ethanol, as has been reported to be the case in Saccharomyces cerevisiae. This production showed a ten-fold increase when the K1ADHI activity was reintroduced in the null mutant and cells were cultivated under oxygen-limiting conditions. Differently from S. cerevisiae, glycerol is poorly accumulated in K. lactis adh null mutants.
在乳酸克鲁维酵母中鉴定出了四个编码乙醇脱氢酶（ADH）活性的基因。由于该酵母中存在多种ADH同工酶，通过基因置换构建的各个基因的突变体未产生明显的表型。我们将这些突变体进行杂交，并开发了一种筛选程序，该程序使我们能够鉴定出缺乏多种ADH活性的菌株。对adh三突变体的分析表明，每种活性都赋予细胞以乙醇作为唯一碳源生长的能力。相反，adh缺失菌株无法在该底物上生长，这表明乳酸克鲁维酵母细胞中不存在其他重要的ADH活性。在adh缺失突变体中，我们还发现了乙醇的残留产生，正如在酿酒酵母中所报道的情况一样。当在缺失突变体中重新引入K1ADHI活性并在限氧条件下培养细胞时，这种产生增加了十倍。与酿酒酵母不同，甘油在乳酸克鲁维酵母adh缺失突变体中积累较少。
