Innovative metabolic pathway design for efficient L-glutamate production by suppressing CO2 emission
Innovative metabolic pathway design for efficient L-glutamate production by suppressing CO2 emission
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DOI：
10.1263/jbb.103.262
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发表时间：
2007-03-01
影响因子：
2.8
通讯作者：
Yasueda, Hisashi
中科院分区：
文献类型：
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作者：
Chinen, Akito;Kozlov, Yuri I.;Yasueda, Hisashi
在谷氨酸棒杆菌的L-谷氨酸(L-谷氨酸)生物合成途径中，以1摩尔的葡萄糖为原料，以1摩尔的二氧化碳为代价合成1摩尔的L-谷氨酸，最高理论产率为81.7%。我们设计了一种利用磷酸酮醇酶(PKT)绕过释放二氧化碳的丙酮酸脱氢酶反应高效生产L-谷氨酸的创新途径，从而将L-谷氨酸从葡萄糖中的最大理论产率提高到了98.0%(120%摩尔/摩尔L-谷氨酸产生/葡萄糖消耗)。从动物双歧杆菌中克隆了编码PKT的XFP基因，并在CSPB启动子的作用下在粘胶双歧杆菌中高效表达。对一株产L-谷氨酸的谷氨酸杆菌(OdhA)进行了功能酶的检测。将含有XFP基因的产生菌和不含XFP基因的产生菌在控制发酵系统中进行培养，结果表明，表达XFP基因的菌株的L-谷氨酸产量明显高于出发菌株，且对CO_2的释放有抑制作用。因此，我们可以通过将动物芽孢杆菌的PKT途径导入到谷氨酸杆菌的L-谷氨酸代谢中，从而成功地提高L-谷氨酸的产量，并且这种新型的代谢设计将能够使L-谷氨酸的产量超过传统的葡萄糖生物合成代谢途径所获得的最大理论产量。
In the pathway of L-glutamic acid (L-Glu) biosynthesis in Corynebacterium glutamicum, 1 mol of L-Glu is synthesized from 1 mol of glucose at a cost of I mol of carbon dioxide (CO2), with a maximum theoretical yield of 81.7% by weight. We have designed an innovative pathway for efficient L-Glu production employing phosphoketolase (PKT) to bypass the CO2-releasing pyruvate dehydrogenase reaction, thereby increasing the maximum theoretical yield of L-Glu from glucose to up to 98.0% by weight (120% mol/mol L-Glu produced/glucose consumed). The xfp gene encoding PKT was cloned from Bifidobacterium animalis and overexpressed under the strong cspB promoter in C. glulamicum. A functional enzyme was detected in an L-Glu-producing strain of C. glutamicum (odhA). When cells of this producer strain with the xfp gene and those without the XfP gene were cultivated in a controlled fermentation system, the L-Glu production yield of the strain expressing the xfp gene was much higher than that of the original strain, coupled with the suppression of CO, emission. Consequently, we could successfully enhance L-glutamate production by installing the PKT pathway of B. animalis into C. glutamicum L-Glu metabolism, and this novel metabolic design will be able to increase L-Glu production yield beyond the maximum theoretical yield obtained from the conventional metabolic pathway of biosynthesis from glucose.