Studies On The Lactase Production From Aspergillus Oryzae

The present study mainly concerned on the related studies of lactase produced by Aspergillus oryzae LAO-0703, including optimization of germ culture medium and the time of germ culture, of zymolytic culture medium at liquid state, of zymolytic condition at liquid state, and analysis of zymolysis at solid state and characterization.Bran powder contains much plenty of nutrimental substances which can effectively accelerate thalli's growth. After experiments related to germ culture using single-factor and orthogonal design, the optimum condition of culture was determined. The optimum time of culture was 11 hours, and the optimum components were: glucose 2.50%, barm 2.00%, KH₂PO₄0.75%. The weight of thalli could attain 14.53g (wet) at this condition.A.oryzae lactose was an induced enzyme, whose vitality could be improved by the induced factor. After studying, we found that bran powder and orange peel powder could induce it very well, improving its vitality significantly.A. oryzae lactose was a kind of enzyme outside the cell wall, which could be separated and extracted without destroying the cell wall. This kind of lactose enzyme could not only be cultured at solid state, but also be produced using deeply culture at liquid state. During the course of culture, the enzyme was exuded into the medium, and it's very convenient to separate and extract with its lower zymolytic cost. After experiments related to enzyme produced by zymolysis at liquid state using single-factor and orthogonal design, the optimum components of zymolytic medium were determined: lactose 1.1%, peptone 0.5%, KH2PO4 2.0%, bran powder 1.5%, and orange peel powder 1.0%. The optimum condition for zymolysis was as follows: quantity of inoculation 10%, temperature 30℃, initial pH 5.5, quantity of bottled liquid 50ml/250ml, revolution of table concentrator 180r/min, and time of culture 4 hours. The vitality of enzyme produced by zymolysis at liquid state under this condition reached 2348U/L, about 15.6 times more than the initial strain.Improved zymolysis at liquid state a little during the course of zymolysis at solid state, adding some nutriment in the culture medium, which increased the vitality of enzyme up to 8.18 U/g, increased 9%. Although enzyme production using zymolysis at solid state required easier equipment, could be spread more easily, and could not easily destroy the structure of enzyme, its shortage was easily polluted by other bacterium. However, the method of zymolysis at liquid state could be controlled more easily, could reduce the pollution of other bacterium, and had higher production efficiency. Consequently, the production of lactase nowadays mainly adopted the latter one.For utilizing and storing this enzyme, we conducted researches on its characteristics. The...