Expression of Global Regulator Lrp Facilitates L-Valine Production in Corynebacterium glutamicum

Abstract:

L-valine is one of the branched chain amino acids widely used in food，feed，and drug industries. In this study，the global regulator Lrp was found to improve L-valine production in C. glutamicum，but slightly inhibit the growth. RT-PCR analysis showed that expression of lrp increased the transcriptional levels of genes related to L-valine biosynthesis （ilvA，ilvBN，ilvC，ilvD） and export （brnFE），which might be the reason for the improved L-valine production. A single amino acid substitution （Arg39Trp） in Lrp reduced the growth inhibition and led to higher L-valine production，especially in L-valine production strain C. glutamicum VWB-1 which contains mutations in the region between lrp and brnF. By co-expressing lrp1 and brnFE in VWB-1，L-valine production of fed-batch fermentation reached 42.1 g/L which was 48.9% increase.