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 argCH 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 argCH 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 argCH 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 argCH-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.