Glucoamylase Fermentation Process Optimization And The AppLication Of The Crude Glucoamylase Broth In The Process Of Alcohol Fermannations

Glucoamylase is the core product of the industrial enzymes in China. Its production has been the first in Chinese enzyme industry and its export also comes to a large scale.However the current problem is that the product price has dropped close to the manufacturing cost and the producers get little profit.Therefore it is great important to optimize the produce process, shorten the fermention cycle and reduce its cost price.The process of Aspergillus niger producing glucoamylase （provided by Nanyang Tianli Enzyme Company） were carried out in the artile by single factor tests and orthogonal tests. The Complete synthetic mediumand the effects on the glucoamylase production by different nitrogen sources,carbon sources,corn steep liquor were studied. The components of medium and fermention process were optimized. Larger scale test in fermenter of 5 cubic metres was carried out to further optimize the glucoamylase producing process.The results were as follows:The glucoamylase producing process was optimized by single factor tests and orthogonal tests:The optimum shake flake medium components:12% maize starch,3% digested soybean meal,1% corn steep liquor. The optimum fermentation conditions:the incubation temperature 34℃, inoculum concentration 5%,initial pH 4.7, fermentation period 144h. Under optimal conditions, the production level of 17543U/mL was obtained, increased by 22.46% than orignal conditions. Production level of 35875U/mL was obtained in a 5 cubic metre fermenter in 90h under original conditions. After optimization production level reached 39377U/mL in 75h, enzyme activity increased by 9.76%,meanwhile,the fermentation period was shortened by 16.7%.Application of the novel crude liquid glucoamylase in the alcohol fermentation process.The optimum pH of crude liquid glucoamylase is 4.6, The optimum temperature is 65℃, K⁺、Mg²⁺ and Ca²⁺ can enhance the activity of crude liquid glucoamylase, while Ag⁺、Fe²⁺ and Cu²⁺ can inhibit the rude liquid glucoamylase activity with different degrees. Zn²⁺、Ba²⁺ and EDTA show little effects on the activity of the crude liquid glucoamylase.It can save 6.41 million （?） every year by using the crude liquid glucoamylase to produce 0.9 million tons of fuel ethanol. Moreover, the ethanol yield is increased 0.45% than the same unit of finished glucoamylase and saved 20% of inorganic salt. Thus, the application of the crude liquid glucoamylase in the alcohol fermentation process could create considerable economic value and eliminate the pollution in the glucoamylase production.