Optimization Of Production Technology Of Nattokinase

Nattokinase (NK) is an alkaline serine protease enzyme which is produced by Bacillus. According to research found that the protease can prevent and treat thromboembolic disease, is a new kind of ideal dissolving suppositories. At present, the production of NK mainly adopts liquid-state fermentation with large energy consumption and low yield. However, solid-state fermentation can make up for these shortcomings. This paper studies solid-state fermentation production process of the NK, which has important significance on the development and utilization of it.Based on laboratory research, this paper optimize the productive technology of nattokinase solid-state fermentation, complete the enlarge production, and study the production technology of the NK product.From the single factor experiment, solid-state fermentation medium and culture conditions were studied. Results show that adding inorganic salt can’t improve the enzyme activity, so that our medium ingredients remain unchanged. We also found that the optimum growth temperature of Natto bacillus is 37 ℃, the optimum temperature for enzyme production is 28 ℃, and bacteria growth and product synthesis was fully correlated. On the basis of the other culture conditions are fixed, we choose 16 h of incubation time for seed liquid. When the fermentation begins to 40h, adding 20% nutrition powder, NK enzyme activity can be stable in 13500 IU/g, increased by 35% than before.The results of ten times magnification test show that when the fermentation level achieve the best, the operating factors were determined as follows:the basin for fermentation device,50% water content,12.5% inoculum size,300g A, fermentation temperature 28℃, fermentation time 65h. Eventually enzyme activity can be stable in 10000 IU/g.By 100 times magnification experiments, in condition of 55% water content, 12.5% inoculum size,2200g A, fermentation temperature 28℃,60-65% humidity, fermentation time 65h, the NK activity can reach to 10000 IU/g. Fermentation ability was stable through repeatability tests. The process completed the transition of the production scale from 10 grams to kilo, which can be used in industrialized production of NK.Through the study of production process of NK product, we have finished producing method. First, get thick liquid with 0.9% saline for extraction of fermented products, then add 40% I as the protectant for drying,40℃ drying temperature,4-4.5h the drying time, finally we get NK products with enzyme activity of 27135 IU/g and the 78.22% recovery rate.Two years ofNK preservation test guaranteed the stable enzyme activity ofNK under the corklition of 28 ℃.