Isolation of a high-yield mutant strain for L-proline production and its fermentation conditions

L-Proline-producing mutant strains were developed by exposing L-glutamic acid-producing bacteria to N-metyl-N-nitro-nitrosoguanidine and UV irradiation. A L-histidine auxotroph of Corynebacterium acetoacidophilum RYU3161 (KCTC 0616BP), which was resistant to sulfaguanidine and proline analogs (DHP, AZC, TAG), was isolated. The activity of the mutant strain's gamma-glutamyl kinase was 45% higher than that of the parent strain. The optimum level of L-histidine for production of L-proline was 0.16 g/l. In a 5-1 jar fermenter, the mutant strain produced L-proline at a high concentration (35 g/l) level within 48 h of cultivation.