Enhanced production of L-arginine by expression of Vitreoscilla hemoglobin using a novel expression system in...

Corynebacterium crenatum SYPA 5-5 is an aerobic and industrial L: -arginine producer. It was proved that the Corynebacterium glutamicum/Escherichia coli shuttle vector pJC1 could be extended in C. crenatum efficiently when using the chloramphenicol acetyltransferase gene (cat) as a reporter under the control of promoter tac. The expression system was applied to over-express the gene vgb coding Vitreoscilla hemoglobin (VHb) to further increase the dissolved oxygen in C. crenatum. As a result, the recombinant C. crenatum containing the pJC-tac-vgb plasmid expressed VHb at a level of 3.4 nmol g(-1), and the oxygen uptake rates reached 0.25 mg A(562)(-1)  h(-1) which enhanced 38.8% compared to the wild-type strain. Thus, the final L: -arginine concentration of the batch fermentation reached a high level of 35.9 g L(-1), and the biomass was largely increased to 6.45 g L(-1), which were 17.3% and 10.5% higher than those obtained by the wild-type strain, respectively. To our knowledge, this is the first report that the efficient expression system was constructed to introduce vgb gene increasing the oxygen and energy supply for L: -arginine production in C. crenatum, which supplies a good strategy for the improvement of amino acid products.