Control of nitrate concentration in fermentations of Corynebacterium glutamicum

A nitrate control system has been devised for the maintenance of stable nitrate concentrations throughout fed‐batch fermentations of Corynebacterium glutamicum. The feedback control system was based on the use of a nitrate‐ion‐selective electrode to directly monitor the nitrate levels in the fermentor and an automatic controller to activate a nitrate feed pump. The electrode which was used for controlling the nitrate level was stable through‐out the fermentation period. The apparent maximum specific growth rate, biomass production, protein production, biomass yields on glucose and nitrate, and amino acid production were all optimal at approximately 50mM nitrate.