Enhancement of pyruvate productivity in Torulopsis glabrata:: Increase of NAD+ availability
Enhancement of pyruvate productivity in Torulopsis glabrata:: Increase of NAD+ availability
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DOI：
10.1016/j.jbiotec.2006.04.014
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发表时间：
2006-11-01
影响因子：
4.1
通讯作者：
Chen, Jian
中科院分区：
文献类型：
--
作者：
Liu, Liming;Li, Yin;Chen, Jian
本研究旨在通过提高NAD(+)的利用率来提高多种维生素营养缺陷型光滑球曲霉的丙酮酸产量。我们研究了两种提高NAD可用性的策略。补充NAD(+)的前体烟酸(NA)，并结合外加乙醛作为外电子受体，提高乙醇脱氢酶的活性。在发酵液中添加8 mg L(-1)NA，可显著提高葡萄糖消耗率(48.4%)和丙酮酸浓度(29%)。通过亚硝胺诱变，筛选出一株乙醇利用突变株WSH-13。与出发菌株相比，突变株WSH-13的乙醇脱氢酶活性提高了约110%，并能以乙醇为唯一碳源生长(1.8g L干重)。在有葡萄糖培养条件下，添加4 mg L(-1)乙醛可显著提高葡萄糖消耗率(26.3%)和丙酮酸产量(22.5%)，但NADH/NAD(+)比值降至0.22。在较高的溶解氧浓度下，乙醛不影响葡萄糖和能量代谢。但在较低的DO浓度(20%)下，将突变株发酵液中的乙醛浓度维持在4 mg L(-1)时，NAD‘浓度升高，而NADH浓度下降。结果表明，丙酮酸产生率、葡萄糖丙酮酸产率和丙酮酸浓度分别比对照(不加乙醛)提高68%、44%和45%。通过提高NAD‘的利用率来提高光滑酵母的糖酵解通量和丙酮酸产量的策略可能为提高酵母代谢产物的生产率提供了一种替代途径。(C)2006爱思唯尔B.V.保留所有权利。
This study aimed at increasing the pyruvate productivity from a multi-vitamin auxotrophic yeast Torulopsis glabrata, by increasing the availability of NAD(+). We examined two strategies for increasing availability of NAD'. To supplement nicotinic acid (NA), the precursor of NAD(+); and to increase the activity of alcohol dehydrogenase integrating with addition acetaldehyde as exterior electron acceptor. The addition of 8 mg l(-1) NA to the fermentation medium resulted in a significant increase in the glucose consumption rate (48.4%) and the pyruvate concentration (29%). An ethanol-utilizing mutant WSH-13 was screened and selected after nitrosoguanidine mutagenesis of the parent strain T glabrata CCTCC M202019. Compared with the parent strain, the alcohol dehydrogenase activity of the mutant WSH-13 increased about 110% and the mutant could utilize ethanol as the sole carbon source for growth (1.8 g l(-1) dry cell weight). When growing with glucose, the addition of 4 mg l(-1) acetaldehyde to the mutant WSH-13 culture broth led to a significant increase in the glucose consumption rate (26.3%) and pyruvate production (22.5%), but the ratio of NADH/NAD(+) decreased to 0.22. Acetaldehyde did not affect the glucose and energy metabolism at high dissolved oxygen (DO) concentration. However, at lower DO concentration (20%), maintaining the acetaldehyde concentration in the mutant culture broth at 4 mg l(-1) caused an increased NAD' concentration but a decreased NADH concentration. As a consequence, the pyruvate production rate, the pyruvate yield on glucose and the pyruvate concentration were 68, 44 and 45% higher, respectively, than the corresponding values of the control (without acetaldehyde). The strategy for increasing the glycolytic flux and the pyruvate productivity in T glabrata by increasing the availability of NAD' may provide an alternative approach to enhance the metabolites productivity in yeast. (c) 2006 Elsevier B.V. All rights reserved.