Heterologous and homologous expression of the arginine biosynthetic argC~H cluster from Corynebacterium crenatum for improvement of (L) -arginine production.

The genes involved in L: -arginine biosynthesis in Corynebacterium crenatum are organized as the argCJBDFRGH cluster like in Corynebacterium glutamicum. However, the argC~H cluster of the C. crenatum SYPA 5-5, which is an industrialized L: -arginine producer, had a lethal mutation occurring in the ArgR repressor encoding gene. The argC~H cluster with an inactive argR was overexpressed in E. coli and C. crenatum. In the recombinant E. coli JM109 enzyme activities were increased, and more L: -arginine was found in the supernatants from L: -glutamine. When the argC~H cluster was overexpressed in C. crenatum under its native promoter Parg, L: -arginine production was increased by 24.9%, but the presence of the recombinant plasmid pJC-9039 had a negative effect on cell growth. Surprisingly, the DO value of the recombinant strain dropped gently and stayed at a lower level from 24 h to the end of fermentation. The results demonstrated an increasing utilization of oxygen and the distinct enhancement of unit cell L: -arginine yields with the cluster argC~H-bearing in C. crenatum SYPA-9039. This study provides a kind of Corynebacteria with improved L: -arginine-producing ability and an efficient elevation for producing amino acid. Moreover, the promoter Parg would be used as a valid promoter to express objective genes for metabolic engineering in Corynebacteria.