食品科学

• 生物工程 • 上一篇    下一篇

利用玉米芯水解液产苹果酸的戴尔根霉突变菌株选育及代谢分析

孙 婷1,杨 英2,王华林1,汪海涛1,吴学凤1,张 旻1,陈小举1,潘丽军1,姜绍通1,李兴江1,*   

  1. 1.合肥工业大学生物与食品工程学院,安徽 合肥 230009;2.安徽建筑大学环境与能源工程学院,安徽 合肥 230601
  • 出版日期:2015-08-15 发布日期:2015-08-17

Mutation and Metabolism Analysis for a Malic Acid-Producing Rhizopus delemar Strain Utilizing Corn Cob Hydrolysate

SUN Ting1, YANG Ying 2, WANG Hualin1, WANG Haitao1, WU Xuefeng1, ZHANG Min1, CHEN Xiaoju1, PAN Lijun1,JIANG Shaotong1, LI Xingjiang1,*   

  1. 1. School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei 230009, China;
    2. School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China
  • Online:2015-08-15 Published:2015-08-17

摘要:

诱变筛选发酵玉米芯水解液高产苹果酸的根霉属菌株,并对其进行代谢分析,研究其高产苹果酸的机理。对分离得到的菌株进行ITS序列鉴定,进一步利用软X射线辐射对菌种进行诱变筛选、对出发菌株和突变菌株的相关酶活力进行测定及代谢通量分析。利用软X射线辐射结合丙烯醇平板筛选乙醇脱氢酶缺陷型菌株,得到突变株-1,发现其乙醇脱氢酶基因的3 处密码子突变为“TAA”,阻断了突变菌株的乙醇代谢途径。进而利用软X射线辐射结合氟乙酸平板筛选乙醛酸循环缺陷型菌株,得到复合突变株-2,降低了副产物富马酸及琥珀酸的产量。复合突变株-2的葡萄糖-6-磷酸脱氢酶中几处NADP(H)结合位点发生突变,增加了糖酵解和磷酸戊糖两种途径的相互作用,促进了其戊糖代谢。经过两步分离筛选,得到的复合突变株-2能发酵玉米芯水解液高产苹果酸,且减少了副产物乙醇、富马酸、琥珀酸的生成。复合突变株-2的苹果酸产量占代谢物总产量的比例由出发菌株的71%增加到91%,苹果酸产量增大1 倍,研究成果对工业化利用突变菌株生产苹果酸具有重要意义。

关键词: 苹果酸, 玉米芯水解液, 代谢通量分析, 葡萄糖-6-磷酸脱氢酶

Abstract:

High-level production of malic acid by fermentation of corn cob hydrolysate with an isolated Rhizopus delemar
strain was expected. Then metabolic analysis and research of the underlying mechanism were carried out. Phylogenetic
analysis based on ITS region sequences was carried out for the identification of X-ray-induced mutant strains, and the key
enzyme activities and metabolic flux were also analyzed. The results showed 3 “TAA” codons in the alcohol dehydrogenase
gene of the anti-allyl mutant strain, which interrupt the pathway of ethanol metabolism. The breeding for the antifluoroacetate
mutant strain succeeded to decrease the flux of fumaric and succinic acid. Some NADP (H)-binding loci were
mutated in the G6PDH gene of the mutant, probably leading to increased interaction of Embden-Meyerhof-Parnas pathway
with Hexose-Monophophate pathway and improved pentose metabolism. After two-step breeding and regulation for this
isolated strain, the production of malic acid was enhanced markedly; the formation of ethanol, fumaric acid and succinic acid
were decreased simultaneously. Compared with the parent strain, the proportion of malic acid in mutant strain-2 increased to
91% from 71% and the yield of malic acid was increased markedly, which is of significance for deep industrial development.

Key words: malate, corn cob hydrolysate, metabolic flux analysis, glucose-6-phosphate dehydrogenase

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