Enhanced Cadaverine Production by Recombinant Corynebacterium Glutamicum with Response Regulator DR1558 at low pH Conditions

Background: Corynebacterium glutamicum is used industrially to produce various bio-based organic acids. However, it is often cultivated under abiotic stress conditions, such as low pH, which can reduce both cell growth and the yield of the target compound. Here, a response regulator from Deinococcus radiodurans, DR1558, was introduced into a recombinant C. glutamicum strain expressing lysine decarboxylase (cadA) to enhance cadaverine production at acidic pHs.Results: During batch cultivation under acidic conditions, 6.4 g/L of cadaverine was produced by the recombinant C. glutamicum strain expressing cadA and dr1558; this yield was 1.7-fold higher than that produced by a recombinant C. glutamicum strain expressing only cadA. Transcriptional analysis revealed altered expression levels of stress defense- and cadaverine biosynthesis-related genes in the recombinant C. glutamicum strain expressing dr1558. During fed-batch cultivation, the recombinant C. glutamicum strain expressing cadA and dr1558 showed a 2.4-fold increase in cadaverine production compared to that produced by the recombinant C. glutamicum strain expressing only cadA. The cell growth of C. glutamicum expressing both cadA and dr1558 increased markedly during fed-batch cultivation at acidic pH.Conclusion: These results indicated that the response regulator dr1558 altered the expression of genes involved in metabolic pathways and stress defense mechanisms in C. glutamicum. Furthermore, C. glutamicum expressing the D. radiodurans dr1558 can be used to produce bio-based organic acids by fermentation in processes requiring acidic conditions.