Analysis of strain-specific genes in glutamic acid-producing Corynebacterium glutamicum ssp. lactofermentum AJ 1511

Strains of the bacterium, Corynebacterium glutamicum, are widely used for the industrial production of L-glutamic acid and various other substances. C. glutamicum ssp. lactofermentum AJ 1511, formerly classified as Brevibacterium lactofermentum, and the closely related C. glutamicum ATCC 13032 have been used as industrial strains for more than 50 years. We determined the whole genome sequence of C. glutamicum AJ 1511 and performed genome-wide comparative analysis with C. glutamicum ATCC 13032 to determine strain-specific genetic differences. This analysis revealed that the genomes of the two industrial strains are highly similar despite the phenotypic differences between the two strains. Both strains harbored unique genes but gene transpositions or inversions were not observed. The largest unique region, a 220-kb AT-rich region located between 1.78 and 2.00 Mb position in C. glutamicum ATCC 13032 genome, was missing in the genome of C. glutamicum AJ 1511. The next two largest unique regions were present in C. glutamicum AJ 1511. The first region (413-484 kb position) contains several predicted transport proteins, enzymes involved in sugar metabolism, and transposases. The second region (1.47-1.50 Mb position) encodes restriction modification systems. A gene predicted to encode NADH-dependent glutamate dehydrogenase, which is involved in L-glutamate biosynthesis, is present in C. glutamicum AJ 1511. Strain-specific genes identified in this study are likely to govern phenotypes unique to each strain.