| By separate factors tests and orthogonal experiments,the optimum fermentation conditions of aminoacylase-producing Aspergillus oryzae were determined, as follows (p/g L-1),glucose 40,sucrose 10,soluble starch 20,peptone 2.5. potato juice 1000ml, inoculation volume 4%and fermentation temperature 30℃,rotation speed 100rmin-1.The highest total enzyme activity,7338μ,was obtained after fermentation for 42h, increased by 279% compared with the original value of 2627μbefore optimization.We dicussed partial characteristics of aminoacylase. The optimal pH and temperature of aminoacylase were 7.0 and 40℃respectively. Low-concentration Co2+ (5×10-4mol/L) activated the aminoacylase remarkably while high-concentration substrate lowered the aminoacylase. Five vectors has been used for immobolizing the enzyme and calcium alginate showed to be the best one for it had the slightest influence on the enzyme activity, easy to operate,and low in price, comparing with other fours. The enzymatic charateristic study showed that its optimum temperature didn't change, but the optimum pH and substrat concentration were higher after immobilization. The stability of immobolized enzyme to acid, alkaline and heat rised as well.The aminoacylse from Aspergillus oryzae was used to resolute racemic phenylalanine to obtain D-phenylalanine. After catalyzing process, we took two methods to separate D-phenylalanine.In end,L-phenylalanine was obtained with 98% optical purity in 84.8% yield, D-phenylalanine was obtained with 92.3% optical purity in 89.5% yield.
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