Lin Jinping, Liu Qinghai, Su Erzheng, Wei Dongzhi, Yang Shengli
State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
Appl Microbiol Biotechnol. 2008 Oct;80(5):831-9. doi: 10.1007/s00253-008-1602-3. Epub 2008 Aug 5.
Industrial bakers' yeast strain Saccharomyces cerevisiae LH1 was selected for asymmetric reduction of ethyl benzoylacetate to (S)-ethyl 3-hydroxy-3-phenylpropionate. Higher reductive efficiency and higher cofactor availability were obtained with the alternation of cultivation condition (mainly growth medium). Compared to the bioreduction by yeast cells grown in malt extract (ME) medium, the concentration of substrate was increased 25-fold (up to 15.6 g/l) in the yeast peptone dextrose (YPD)-grown cells mediated bioreduction with 97.5% of enantioselective excess of (S)-product. The proteomic responses of S. cerevisiae LH1 cells to growth in aerobic batch cultures fed with either YPD or ME medium were examined and compared. Among the relative quantities of 550 protein spots in each gel, changes were shown in the expression level of 102 intracellular proteins when comparing YPD gel to ME gel. Most of the identified proteins were involved in energy metabolism and several cellular molecular biosynthetic pathway and catabolism. For YPD-grown yeast cells, not only enzymes involved in nicotinamide adenine dinucleotide phosphate regeneration, especially 6-phosphogluconate dehydrogenase, but also alcohol dehydrogenase 1 and D: -arabinose 1-dehydrogenase which had been demonstrated activity toward ethyl benzoylacetate to (S)-hydroxy ester were significantly upregulated. These changes provided us insight in the way the yeast cells adapted to a change in cultivation medium and regulated its catalytic efficiency in the bioreduction.
工业烘焙酵母菌株酿酒酵母LH1被选用于将苯甲酰乙酸乙酯不对称还原为(S)-3-羟基-3-苯基丙酸乙酯。通过改变培养条件（主要是生长培养基），可获得更高的还原效率和更高的辅因子利用率。与在麦芽提取物（ME）培养基中生长的酵母细胞进行的生物还原相比，在酵母蛋白胨葡萄糖（YPD）培养基中生长的细胞介导的生物还原中，底物浓度提高了25倍（高达15.6 g/l），(S)-产物的对映体过量率为97.5%。研究并比较了酿酒酵母LH1细胞在以YPD或ME培养基为补料的好氧分批培养中的蛋白质组学响应。在每块凝胶中550个蛋白质斑点的相对量中，比较YPD凝胶和ME凝胶时，有102种细胞内蛋白质的表达水平发生了变化。大多数已鉴定的蛋白质参与能量代谢以及几种细胞分子生物合成途径和分解代谢。对于在YPD培养基中生长的酵母细胞，不仅参与烟酰胺腺嘌呤二核苷酸磷酸再生的酶，特别是6-磷酸葡萄糖酸脱氢酶，而且已证明对苯甲酰乙酸乙酯还原为(S)-羟基酯具有活性的乙醇脱氢酶1和D-阿拉伯糖1-脱氢酶都显著上调。这些变化为我们深入了解酵母细胞如何适应培养基变化并调节其在生物还原中的催化效率提供了思路。
