The Construction Of An Guanosine-Producing Engineering Strain And The Primary Study On The Fermentation Conditons

According to the theory of metabolic control fermentation, the dissertation focuses on the the construction of an guanosine-producing engineering strain and the primary study on the fermentation conditions. The main research contents and results are as follows: 1. The method of ion exchange chromatography was defined to determinate guanosine concentration quantitatively in the fermentation broth. The separation conditions of this method was optimized and compared with paper chromatography method. Both accuracy and precision are better than that of paper chromatography. 2. By means of protoplast transformation, the plasmid pUBLW2 containing SGr gene was transformed to the recipient-the guanosine-producing strain Bacillus subtilis TA208. The engineering strain TA424(pUBLW2/Km~r+SG~r) with higher resistence was finally obtained. 3. The batch fermentation conditions of the transformant TA424(pUBLW2/Km~r+SG~r) in shake flask was studied in this dissertation. The proportions of seed medium and fermentation medium were optimized by uniform design experiment and pattern recognition . Under the optimum condition, strain TA424(pUBLW2/Km~r+SG~r) could produce guanosine 24.8g/L by shaking flask batch fermentation. 4. The guanosine batch fermentation kinetics were studied based on the datas got from 5-liter fermentor fermentation. Three kinetic models were constructed which could perfectly reflect the growth ,product formation and substrate consumption in the process of batch fermentation.