Studies on the Effect of Initial Glucose Concentration and Dilution Rate of Glutamic Acid Production using Continuous Process

Author : Carlos, Romel Manansala
Major Adviser : Chay, Pham Binh
Committee Members :
Year : 1991
Month : October
Type : Thesis
Degree: BS
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Fermentation process of glutamic acid production was carried out using Corynebacterium glutamicum CgAC 1188 either in a batch mode in a stirred tank fermenter or in a continuous mode in a stirred tank fermenter coupled with a ceramic filtration unit. In a batch mode, the effect initial glucose concentration was studied. The optimum initial glucose concentration was 100 g/L and was applied in a continuous mode. The maximum glutamic acid concentration was 39.98 g/L achieved after 48.71 hours of fermentation which was 4.80 and 5.49 times greater than the yields of 150 and 200 g/L initial glucose concentration, respectively. Increasing the amount of initial glucose concentration above 100 g/L causes substrate inhibition. Lowering in the concentration of glutamic acid concentration during the third day of fermentation may have been caused by further conversion of glutamate to other amino acids and side products. The optimum dilution rate was 0.0783 hr-1 for the continuous glutamic acid production resulting to specific productivity and Yp/x values of 0.27 g/L·hr and 7.29, respectively. A further increase in the dilution rate resulted to high biomass concentrations but low specific product formation.

The optimum continuous process coupled with a ceramic membrane filter for glutamic acid production increased the amount of glutamic acid produced and volumetric productivity by factors of 1.76 and 6.73, respectively compared to the conventional batch process. The coupling with a ceramic membrane filter reduced the conversion of glutamate to other amino acids and side products while allowing continuous removal of cell-free glutamic acid minimizing downstream processing for the separation of cells from the fermentation broth.

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