Studies On The Optimical Conditions And The Kinetics Of 2-keto-D-gluconic Acid By Fed-batch Fermentation

The technique of iodometry determining the mass concentration of 2-keto-D-gluconic acid was established in fermentation broth. Utilizing Pseudomonas fluorescence AR4, the optimization condition of the initial concentration was studied on 2KGA batch fermentation.The optimization conditions and kinetic characteristic of fed-batch fermentation were investigated. The main research results are as follow:The optimal conditions of iodometry which determined the concentration of 2KGA in fermentation broth, was established. According to the precusion test, stability test, reproducibility test and recovery test, the accuracy of the technique of iodometry is high.The determination result is stable and reliable.The fermentation cycle, conversion and production intensity of the different initial glucose concentration on 2KGA batch fermentation was studied.The optimal initial glucose concentration of 140 g/L was determined on batch fermentation. Under such condition the fermentation cycle and productivity were 16 h and 96.465%, respectively.The research results for feeding time, feeding pattern, carbon nitrogen ratio of the feeding medium,and total glucose concentration of fed-batch fermentation were studied. Experimental results established that the total glucose concentration of 2KGA fed-batch fermentation can reach 300 g/L. The initial glucose concentration is 140 g/L. When residual glucose concentration falls to 20 g/L, we choose the feeding pattern of constant speed flow. Carbon nitrogen ratio is 20/1 in the feeding medium. Finally the production of 2KGA reaches 332.574 g/L. Fermentation conversion ratio is 88.271%.The fermentation cycle and average production are 52 h and 6.396 g/L·h, respectively.The kinetic models of pseudomonas fluorescence AR4 on fed-batch fermentation 2KGA are as follows:Kinetic models of cell growth: Before feeding: X = 2 .433/[1 +4.415×exp(?1.163t)],P<0.0250; In between feeding: X≈2 .641,且μ≈D; After feeding: X = 4 .262/[1 +243.715×exp(?0.191t))] ,P<0.0012。Kinetic model of 2KGA generation: P = 32 .486+5.992t,r=0.9859Kinetic models of glucose consumption: Before feeding: S =152.236-11.484t,r=0.9996;In between feeding: S = 4. 997+5.059×exp(0.064t),P<0.0145; After feeding: S = 144 .220?2.762t,r=0.9976。The above models reflect the production process of 2KGA. They can be used as basis for further research on the fermentation conditions of 2KGA and control of reactor.