Engineering Corynebacterium crenatum for construction of L-Ornithine and L-Citrulline producers

Abstract:

[Objective] L-Ornithine and L-Citrulline producers were constructed based on the L-Arginine producer Corynebacterium crenatum SYPA5-5 and their fermentative performances were evaluated. [Methods] argF encoding ornithine carbamoyltransferase (OTC) and argG encoding argininosuccinate synthase (ASS) were deleted respectively in SYPA5-5 to block the biosynthetic pathway that converting L-Ornithine and L-Citrulline to L-arginine. Two recombinant strains SYPA5-5△argF and SYPA5-5△argG were constructed. The influence of different L-arginine concentration on growth and amino acids accumulation of the recombinant strains were determined. [Results] SYPA5-5△argF kept well growth status with the fermentation media supplied with 0.3 g/L L-arginine and the growth rate was similar to SYPA5-5. SYPA5-5△argF had the capacity of producing 21.5 g/L L-Ornithine. On the contrary, L-arginine had no use for SYPA5-5△argG to enhance the productivity of L-Citrulline even though it contributed to improve cell growth. SYPA5-5△argG produced 15.2 g/L L-Citrulline with the original media without adding L-arginine, and it produced 6.8 g/L L-glutamate simultaneously. [Conclusion] Deleting argF and argG respectively in SYPA5-5 made it accumulate high concentration of L-Ornithine and L-Citrulline. These expanded the applied scope of SYPA5-5 in amino acids industry.

Key words:L-Ornithine, L-Citrulline, Corynebacterium crenatum, Ornithine carbamoyltransferase, argF, Argininosuccinate synthase, argG