Screening, Application And Conditions Of Enzyme Production Research Of Bacillus Subtilis Strains With High-Cellulase Yielded

Owing to a variety of physiological functions, Dietary fiber (DF) was praised as "the seventh largest nutrient" of the human body, one of its composition the soluble components (Soluble Dietary fiber, SDF), has a better physiological function than the other composition the insoluble components (Insoluble Dietary fiber, IDF), and has more important applications and research significance. Soybean dregs with its rich cellulose materials and large output in our country, become an ideal source of SDF. However, it has fewer natural SDF, therefore, a certain degree of technical processing in order to improve the SDF content and yield rate must be taken. At present, biotechnology represented by the fermentation technology and enzyme technology is considered one of the most potential technologies, while the choice and identification of bacteria and enzymes is particularly important. Bacillus subtilis, with a number of advantages, making it becomes the first choice of enzyme production and application strain.For above reasons, this paper studied the screening methods of the high-yielding cellulose Bacillus subtilis strain, and its applications of fermentation in preparing soybean dregs SDF,as well as this strain's cellulase production conditions, the results are as follows:1. From the natural, obtained a Bacillus subtilis strain with high cellulose-producing activity, and named as BS-05 according to the order of experimental number. In the natural selection conditions, the strain has high produced cellulase activity, Sodium Carboxymethylcellulose Activity (CMCA) and the Filter Paper Activity (FPA) were 57.27 U/ml and 58.97 U/ml.2. Used the BS-05 strains in fermented soybean dregs, and in conjunction with the homogenization technique, obtained the soybean dregs SDF. After fermentation and homogenization, the yield of the soybean dregs SDF was increased to nearly 4-fold, and the particles become smaller, structure become looser, solubility and water holding capacity and other physical and chemical properties have different degrees of improvement.3. Obtained the best conditions for cellulase production of strain BS-05. Its enzyme production medium composition is:CMC-Na 2%, peptone 2%, yeast extract 2%, NaCl 0.5%, K2HPO4 0.1%, MgSO4·7H2O 0.02%; The optimal culture conditions are:culture temperature 37℃, culture base the initial pH7, inoculum size 5%, incubation time 48h and fermentation medium of liquid volume of 60ml. In the above-mentioned conditions, the strain has highest produced cellulase activity CMCA and the FPA respectively reached at 195.46 U/ml and 174.52 U/ml, is 3.41-fold and 2.96-fold before optimization.4. Obtained some enzyme properties of the cellulase produced by this strain were studied. The result is that:the optimum pH value of the cellulose is 6-7, the activity was stable after maintain 60min under this pH, and the optimum temperature is 55℃, there is still a high activity after maintain 30min at below 65℃. This research may provides parameters for the extension and application of the cellulose produced by BS-05.