代谢工程改造枯草芽孢杆菌促进L-赖氨酸高效合成研究

Metabolic engineering for improving the L-lysine production by Bacillus subtilis

为了构建具有益生功能和L-赖氨酸合成功能的“双功能”枯草芽孢杆菌(Bacillus subtilis)重组菌株,对饲料工业常用的益生菌B.subtilis ACCC11025进行系统的代谢工程改造。结果表明:以来源于谷氨酸棒杆菌(Corynebacterium glutamicum)的lysC^(311)、zwf^(234)和gnd^(361)替换B.subtilis中的thrD、zwf和gnd,即构建重组菌B.subtilis XH4,有利于L-赖氨酸的合成,其产量达到(20.3±1.9)g/L;将B.subtilis中hom替换成来源于C.glutamicum的hom^(59),即构建重组菌B.subtilis XH5,可显著降低副产物积累量,提高L-赖氨酸产量至(23.2±1.7)g/L,且不影响菌体生长;在重组菌B.subtilis XH5中引入C.glutamicum中的DapDH会改变二氨基庚二酸途径(DAP)碳分布进而促进L-赖氨酸的合成,目标重组菌B.subtilis XH6的L-赖氨酸产量达到(25.6±2.3)g/L。

In order to construct a dual-functional B.subtilis with probiotic function and L-lysine production,B.subtilis ACCC11025 was systematically modified.These results indicated that the strain with replacement of thrD,zwf and gnd from B.subtilis by lysC^(311),zwf^(234)and gnd^(361)from C.glutamicum(i.e.,B.subtilis XH4)was beneficial to L-lysine production,and the yield of L-lysine was(20.3±1.9)g/L.In addition,the strain with replacement of hom from B.subtilis by hom^(59)from C.glutamicum(i.e.,B.subtilis XH5)produced(23.2±1.7)g/L of L-lysine without the decrease of cell growth.In addition,the yield of by-products in B.subtilis XH5 was significantly decreased.Moreover,the DapDH from C.glutamicum was introduced into the B.subtilis XH5(i.e,B.subtilis XH6),resulting in the increase of L-lysine production because of the redirection of the carbon flux in DAP pathway.The resulted recombinant strain B.subtilis XH6 produced(25.6±2.3)g/L of L-lysine.