The Mutation Breeding Of The Strain Of High Protease Activity And Reducing The Anti-nutritional Factors

As the development of feed industry, drying up and appearing disadvantages of animalprotein sources, people are beginning to look to other protein sources. Soybean meal, as a qualitiedplant protein source, because of its abundant supply, reasonable amino acid composition, containsisoflavones, fatty acids, minerals and other bioactive substances and nutritional ingredients, startto get people’s attraction increasingly. However, soybean meal has its own limitations: First, is thatsoybean meal is primarily made up of protein macromolecules, cannot be fully absorbed by thebody as the small molecule-protein, oligopeptides and free amino acid. Secondly, soybean mealcontains a variety of antinutritional factors, especially the highest content of phytic acid andtrypsin inhibitor, both are around2%, they not only reduce the use of animals for nutrients, alsoimpact on health.This study carried out in four steps: First of all, according to the transparent circle methodand phenol-forint method, determine the protease activity, proceeding selected strains of highenzyme activities; Second, ultraviolet mutation, in determining the volume induced condition;Third, taking protease, acid-soluble protein, free amino acid, trypsin inhibitors, and phytic acidcontent as indicators, Filter out good strains after mutation, which can improve smallmolecule-protein content and reduce the effect of anti-nutritional factors in fermented soybeanmeal, and make its identification; Last, effectiveness verification on the stability of the superiorstrains. Research results are as follows:1Compare5producing protease strains which stored in laboratory, after a series of filters,finally get one original strains of high protease.2Determination of UV batch mutation condition,30W UV lamps, irradiation from15cm,irradiation on bacteria liquid coated tablet with gradient of10-7strains. This method is stable,reliable, and with strong repetition.3Determination of protein content, through screening protease activity, fermented the contentof acid-soluble proteins and free amino acids in soybean meal, filter out of two bacteria strains,JY14,JY15. After determination of the content of anti-nutritional factors of the two bacteria strains,content of phytic acid and trypsin inhibitor, determining one strain, JY15, compare with theoriginal strain, the determination indicators above show significant differences(p＜0.01). Biological identification with individuals, groups, physiological and biochemical characteristics onthe superior strains JY15, which have identified that strain is Bacillus.4Verification on strain genetic stability, take acid soluble protein content as indicator, forbacteria fermentation raw materials validation, determine the strains are still outstanding even inthe cases of bacteria, this character means that the superior strains is more adaptive-grainedfermentation in the factory.