Enhanced Production of l-Arginine by Expression of Vitreoscilla Hemoglobin Using a Novel Expression System in Corynebacterium crenatum

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.