缬氨酸生产菌株的定向改造及发酵优化  

Direct construction and fermentation optimization of valine producing strain

作　　者：石拓[1] 刘晓倩 范晓光[1] 陈宁[1] SHI Tuo;LIU Xiaoqian;FAN Xiaoguang;CHEN Ning(College of Biotechnology,Tianjin University of Science & Technology,Tianjin 300457,China)

机构地区：[1]天津科技大学生物工程学院,天津300457

出　　处：《食品与发酵工业》2019年第5期19-24,共6页Food and Fermentation Industries

摘　　要：缬氨酸是人体必需氨基酸之一,具有重要的生理生化作用。为进一步提高缬氨酸产量及优化发酵过程的温度控制,从谷氨酸棒杆菌细胞壁肽聚糖合成途径的2个关键基因murA(cgl0352)和murB(cgl0353)入手,从1株缬氨酸生产菌中敲除murA和murB基因构建出重组工程菌株C.glutamicum A301。摇瓶发酵结果显示,该菌株具有温度敏感性,在变温发酵的条件下,能从生长型状态转化为产酸型状态,促进缬氨酸的积累。在5 L发酵罐中采用分段控温策略发酵,即前15 h控温33℃,15 h之后提温至39℃,重组工程菌株的缬氨酸产量达到35.5 g/L,与全程33℃发酵相比提高了55.7%。研究为缬氨酸发酵过程温度控制提供了经验,同时对于谷氨酸棒杆菌的定向改造提供了一种思路。Valine is one of the essential amino acids in human body and has important physiological and biochemical functions. In order to further increase the production of valine and optimize the temperature control of valine fermentation process, two key genes mur A(cgl0352) and mur B(cgl0353) of Corynebacterium glutamicum cell wall peptidoglycan biosynthesis pathway were studied. A recombinant engineering strain C. glutamicum A301 was constructed by knocking out mur A and mur B of a valine producing strain. The shake-flask fermentation results showed that the strain had temperature-sensitive trait. Under the condition of temperature shift fermentation, the state of the strain could be transformed from growth form to amino acid producing form, and the accumulation of valine was improved. Using a two-step temperature control strategy (temperature of 33 ℃ for the first 15 h and then increased the temperature to 39 ℃), the yield of valine from the recombinant strain reached 35.5 g/L, which was 55.7% higher than that using a one-step temperature control strategy (temperature of 33 ℃) in a 5 L fermentor. This study provides experience for controlling temperature for valine fermentation process, and provides an idea for directional transformation of C. glutamicum .

关 键 词：谷氨酸棒杆菌 缬氨酸 定向改造 发酵优化 

分 类 号：TQ922[轻工技术与工程—发酵工程]