Biosynthesis Of Adenosine 5' -Triphosphate By Using Immobilized Yeast Cells

The biosynthesis of ATP by immobilized enzyme/cells have many advantages, such as high efficiency of reactor, low costing of main raw materials, high yield and simplify the last disposal etc. So it has been developed in recent years and become the major production method of ATP. Use immobilized enzyme/cells synthesize ATP should consider the steady of the cell quality, the intension of the immobilized carrier and the operational conditions and so on. To solve the three problems, the cultivation condition of yeast, choose of immobilized carrier and the operational conditions of ATP were investigated in this paper.Some work was selected to study the relations between ATP conversion activity and the cultivation condition of yeast. Such as the cultivation time of the yeast, the germinant rate of the yeast and the rate of consume glucose of the yeast. The different between the bread yeast and the beer yeast in ATP production was also investigated in this paper.A strain of yeast that is of high ATP producing activity was selected.By immobilized carrier experiment, sodium alginate, PVA, gelatin, carrageenin and its mixed supports were investigated in ATP production. Fromthe strength of the carrier, gelatin is a good support. The optimum condition of immobilized yeast by gelatin is: using phosphate buffer of pH=5.8 as solvent, gelatin concentration 10%, immobilized yeast cells 16%, Glutaraldehyde concentration 1.5%, cross linking time 25min.There are some factors may affect AMP conversion activity. On the basis of the experiment results, the mechanism of synthesizing ATP was investigated by use of immobilized yeast cells. The first process of synthesizing ATP is glycolysis and phosphorylation of glucose and the second process is the accumulation of ATP. Mg2+ is the active factor of Embden-Meyerhof Passway (EMP).The experiment results show that the concentration of Mg2+ affects ATP conversion rate little. The optimal synthetic condition is as follows: AMP=5g/L, NaH2PO4=250mmol/L, MgSO4=8mmol/L, glucose=150mmol/L, reaction temperature is 35℃, pH=7.5, reaction time is 3h, reflective liquid: immobilized yeast cells=1.0 : 1.0 and influences speed 75r/min. In this condition, the conversion rate of ATP was maintained at over 90% in 6 times.