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中国精品科技期刊2020
刘宇飞,伏聪,谢雨康,等. 改造枯草芽孢杆菌的乙醛酸旁路合成乙醇酸[J]. 食品工业科技,2023,44(20):143−151. doi: 10.13386/j.issn1002-0306.2023020003.
引用本文: 刘宇飞,伏聪,谢雨康,等. 改造枯草芽孢杆菌的乙醛酸旁路合成乙醇酸[J]. 食品工业科技,2023,44(20):143−151. doi: 10.13386/j.issn1002-0306.2023020003.
LIU Yufei, FU Cong, XIE Yukang, et al. Synthesis of Glycolate by Bacillus subtilis through Glyoxylate Bypass Pathway[J]. Science and Technology of Food Industry, 2023, 44(20): 143−151. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2023020003.
Citation: LIU Yufei, FU Cong, XIE Yukang, et al. Synthesis of Glycolate by Bacillus subtilis through Glyoxylate Bypass Pathway[J]. Science and Technology of Food Industry, 2023, 44(20): 143−151. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2023020003.

改造枯草芽孢杆菌的乙醛酸旁路合成乙醇酸

Synthesis of Glycolate by Bacillus subtilis through Glyoxylate Bypass Pathway

  • 摘要: 为了构建一株可以生产乙醇酸的食品安全菌株,对枯草芽孢杆菌开展了代谢改造。本研究首先利用同源重组手段将外源异柠檬酸裂解酶基因aceA整合到了枯草芽孢杆菌基因组上,构建了出发菌株164MCT-GA,然后利用代谢工程手段进行了乙醇酸合成代谢优化。结果表明,整合外源异柠檬酸裂解酶基因aceA的出发菌株164MCT-GA可以实现以甘油为底物的乙醇酸从头合成,摇瓶发酵产量为0.114 g/L;在此基础上,过表达柠檬酸合成酶基因(citA),加强前体物供应;过表达乙醛酸还原酶基因(yvcT)、敲除乳酸脱氢酶基因(ldh)、磷酸乙酰转移酶基因(pta)、乙酰-CoA转乙酰酶基因(mmgAyhfs),从而减少碳源损失并提高乙醇酸转化率,最终得到的工程菌GA3-52,其摇瓶发酵产量为0.572 g/L,是出发菌株的5倍以上,产率为0.175 g/g甘油,本研究首次在枯草芽孢杆菌中利用乙醛酸循环进行乙醇酸的从头合成,为食品安全菌高产乙醇酸的发酵生产奠定了基础。

     

    Abstract: In order to construct a food-safe strain that could produce glycolate, the metabolic modification of Bacillus subtilis was carried out. In this study, the exogenous isocitrate lyase gene (aceA) was first integrated into the genome of Bacillus subtilis by homologous recombination, and the starting strain 164MCT-GA was constructed. Then the glycolate anabolism was optimized by means of metabolic engineering in the starting strain 164MCT-GA. The results showed that 164MCT-GA could synthesize glycolate with glycerol as substrate, and the yield of shaker fermentation was 0.114 g/L. To increase the supply of the key intermediate substrates, the citrate synthase gene (citA) and the glyoxylate reductase gene (yvcT) were overexpressed by replacing the native promoter with individual T7 promoter. The Bacillus strains were further engineered at multiple loci that included lactate dehydrogenase (ldh), phosphate acetyltransferase (pta) and acetyl-CoA transacetylase (mmgA, yhfs), in an attempt to modulate the carbon flux toward the formation of glycolate with a higher efficiency. The fermentation study revealed that the accumulated concentration of glycolate from the obtained B. subtilis strain GA3-52 reached 0.572 g/L, with a conversion rate of 0.175 g/g glycerol, the titer was more than five times as much as that achieved by 164MCT-GA. Thus, this study constructed a de novo synthesis pathway in B. subtilis, and laid the foundation for the fermentation production of high yield glycolic acid by food safety bacteria.

     

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