表达耐辐射异常球菌IrrE蛋白对产丁二酸大肠杆菌耐渗透压的影响

Influence of expressing IrrE from Deinococcus radiodurans on osmotic stress tolerance of succinate-producing Escherichia coli

摘要:

高渗透压胁迫是降低生物法制备丁二酸生产效率的关键因素之一。为提高丁二酸生产菌株对高渗透压胁迫的耐受性能，本研究考察了外源引入全局调控蛋白IrrE提高大肠杆菌耐高渗透压胁迫性能的可行性。试验结果表明，在不同浓度Na+胁迫下，重组菌生长和发酵性能明显提升。在5 L罐发酵中，重组菌最大细胞干重、糖耗和丁二酸产量比对照菌分别提高了15.6%、22%和23%，表明引入IrrE蛋白可提高菌株对高渗透压胁迫的耐受能力。进一步比较重组菌和对照菌胞内相容性物质海藻糖和甘油的浓度后发现，重组菌胞内海藻糖和甘油浓度明显提高，其最大积累量分别是对照菌的1.3和3.8倍，推测IrrE可通过增加胞内相容性物质的积累提高菌株对高渗透压胁迫的耐受性。

Abstract:

Hyper-osmotic stress is one of the key factors that decrease the efficiency of biological succinic acid production. To increase the osmotic stress tolerance of succinate-producing Escherichia coli, we studied the influence of IrrE, an exogenous global regulator, on cell osmotic stress resistance. Fermentation results showed that cell growth and succinic acid production by the recombinant increased under different Na+ concentrations. Meanwhile, the maximum dry cell mass, glucose consumption and succinic acid concentration increased 15.6%, 22% and 23%, respectively, when fermented in a 5-L bioreactor. Expressing IrrE improved cell resistance to hyper-osmotic stress. Further comparison of intracellular osmoprotectants (trehalose and glycerol) concentrations showed that trehalose and glycerol concentrations in the recombinant increased. This suggested that introducation of IrrE could enhance intracellular osmoprotectants accumulation which conferred cell with improved resistance to osmotic stress.