Nutritional and mutational aspects of lysine production by Corynebacterium glutamicum auxotrophs

Mutants of different auxotrophic natures were developed from one of the regulatory mutants of Corynebacterium glutamicum. All the mutants were examined for the production of lysine, yield based on total sugar, percentage conversion of consumed sugar, and yield per gram dry cell weight, in three different fermentation media in stirred tank fermenter. The mutated MRLH-GHAIO accumulated 38.4 g/L lysine with 43.8% conversion and 2.4 g lysine per gram dry cell weight in FM1 medium while in FM2 medium it gave 32.8 g/L lysine with 39.1% conversion and 2.1g lysine per gram dry cell weight. The other auxotrophic mutant MRLH-LI, T3, MT8, MTA2, HI6, HA5 and GHI3 produced 27.5-33 g/L lysine with 32.22-36.8% conversion in FM1 medium and 25-30.8g lysine with 30.4-37% conversion in FM2 medium the yield per gram dry cell weight was 1.5-1.98 g/g in FM1 and FM2 medium. The yield based on total sugar increased as the amount of lysine increased. Lower yield was recorded in FM3 medium. All the auxotrophic mutants showed higher productivity and conversion efficiency than parent strain.