High-level exogenous glutamic acid-independent production of poly-(¦Ã-glutamic acid) with organic acid addition in a new isolated Bacillus subtilis C10

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• 作者：Huili Zhang^a ; Jianzhong Zhu^a ; ^b ; Xiangcheng Zhu^a ; Jin Cai^a ; Anyi Zhang^a ; Yizhi Hong^a ; Jin Huang^a ; Lei Huang^a ; Zhinan Xu^a ; ^{znxu@zju.edu.cn}
• 关键词：Poly-(¦Ã-glutamic acid) ; Bacillus subtilis C10 ; Organic acids ; Glutamic acid-independent biosynthesis
• 刊名：Bioresource Technology
• 出版年：2012
• 出版时间：July, 2012
• 年：2012
• 卷：116
• 期：Complete
• 页码：241-246
• 全文大小：695 K

文摘

A new exogenous glutamic acid-independent ¦Ã-PGA producing strain was isolated and characterized as Bacillus subtilis C10. The factors influencing the endogenous glutamic acid supply and the biosynthesis of ¦Ã-PGA in this strain were investigated. The results indicated that citric acid and oxalic acid showed the significant capability to support the overproduction of ¦Ã-PGA. This stimulated increase of ¦Ã-PGA biosynthesis by citric acid or oxalic acid was further proved in the 10 L fermentor. To understand the possible mechanism contributing to the improved ¦Ã-PGA production, the activities of four key intracellular enzymes were measured, and the possible carbon fluxes were proposed. The result indicated that the enhanced level of pyruvate dehydrogenase (PDH) activity caused by oxalic acid was important for glutamic acid synthesized de novo from glucose. Moreover, isocitrate dehydrogenase (ICDH) and glutamate dehydrogenase (GDH) were the positive regulators of glutamic acid biosynthesis, while 2-oxoglutarate dehydrogenase complex (ODHC) was the negative one.