Increasing l ‐isoleucine production in Corynebacterium glutamicum by overexpressing global regulator Lrp and two‐component export system Brn FE

Aims To increase the l ‐isoleucine production in C orynebacterium glutamicum by overexpressing the global regulator Lrp and the two‐component export system Brn FE . Methods and Results The brnFE operon and the lrp gene were cloned into the shuttle vector pDXW ‐8 individually or in combination. The constructed plasmids were transformed into an l ‐isoleucine‐producing strain C. glutamicum JHI3‐156, and the l ‐isoleucine production in these different strains was analysed and compared. More l ‐isoleucine was produced when only Lrp was expressed than when only BrnFE was expressed. Significant increase in l ‐isoleucine production was observed when Lrp and BrnFE were expressed in combination. Compared to the control strain, l ‐isoleucine production in JHI3‐156/ pDXW ‐8‐ lrp ‐ brnFE increased 63% in flask cultivation, and the specific yield of l ‐isoleucine increased 72% in fed‐batch fermentation. Conclusions Both Lrp and Brn FE are important to enhance the l ‐isoleucine production in C. glutamicum . Significance and Impact of the Study The results provide useful information to enhance l ‐isoleucine or other branched‐chain amino acid production in C. glutamicum .