Investigation Of Method Using PH Value Feedback Controlling Of Carbon And Nitrogen Source Feeding In Lysine Fermentation

Lysine is the second commodity amino acid in currently world , which was widely used as additives in food, medicine and feed areas. Intermittent fed-batch method and constant substrate concentration fed-batch method controlled manually are the common method used at present. Although the former is simple, the concentration of substrate in fermentation fluctuate largely for the reason of feeding rate not as simultaneously as substrate consumption rate; the latter has complex operation and is not able to guarantee the substrate respond immediately, which results to the lag of addition.This investigation focused on the consumption relationship among ammonia, used as pH regulator, glucose, as well as ammonium sulfate. A method using pH as signal for feedback controlling carbon and nitrogen source feeding in lysine fermentation by feeding the solution mixture with glucose, ammonia and ammonium sulfate was found in this paper, which could regulate pH value and feeding carbon nitrogen source at the same while.Fed-batch fermentations were operated under different concentration conditions of carbon and nitrogen sources, and that consumption ratio among glucose, ammonia and ammonia sulfate 15.7:1:1.64. The mixture solution according to this ratio was added into fermentation broth as pH regulator, simultaneously achieving automatic addition of carbon and nitrogen sources. The results showed that the glucose concentration was maintained in the range of 8 g/L to 16 g/L, and ammonium 1.5 g/L to 3.4 g/L by using pH feedback controlled method. Compared with intermittent feeding and constant substrate concentration feeding, this method resulted in an increase in the concentration of lysine by 3.6% and 17.2% respectively, in lysine productivity by 9.5% and 28.8% respectively, and in the conversion ratio from glucose to lysine by 4.9% and 18.6% respectively.