The Research Of Making Soybean Meal Feedstuffs On Bacillus Subtilis By Mixing Fermentation

Soybean meal is obtained after extraction of soybean oil from soybean. As a by-product of soybean, soybean meal is not only nutrient-rich but also full range of nutrients. And it's a kind of plant protein feed full of balance nutrient content. Soybean meal has high protein content, and is full of water-soluble protein particularly. However, the characteristic of water-soluble protein is high molecular weighty and complex structure. So if soybean meal is directly used for feedstuffs to raise animals, protein in soybean meal will be absorbed in a low absorption rate. Thus it will cause large waste of resources of soybean meal. Then the cost of feeding must increase accordingly.Over the years, according to the actual production conditions enzymatic preparation of soybean meal feed there are also many constraints in enzymatic preparation of soybean meal feed, mainly it is a small number of enzymes used for enzymatic method, so far limited the development of the soybean meal feed industry. In addition, since few types of protease is used for hydrolysis, so that degradation of soybean protein can not be good, bitterness can not simply be removed in the preparation of soybean peptide, thus affecting feed taste, photographed by keeping animals is greatly reduced food consumption in the course of feeding animals. Compared with the enzymatic, microbial fermentation method has many advantages of shortening the fermentation period, reducing the cost of soybean meal, has a bright future. Solid state fermentation method can achieve more large-scale production, production costs of preparing of soybean meal feed can be decreased apparently, almost no pollutants of polluting the environment is discharged in solid-state fermentation process. Therefore, the solid-state fermentation in the feed processing industry will occupy more and more important position.It has been studied about soybean meal by Bacillus subtilis through solid-state fermentation from the view of protease activity. It is not reported about the study of soybean meal by Bacillus subtilis through solid-state fermentation from the view of both protease activities and soybean peptide's conversion. According to the situation of secreting protease in the course of Bacillus subtilis in combination with Aspergillu. It has been studied deeply in this thesis about making soybean meal feedstuffs on Bacillus subtilis in combination with Aspergillu oryzae or Bacillus subtilis in combination with Aspergillu niger by mixing fermentation from the view of both protease activity and soybean peptide's conversion, in order to hydrolyzing soyprotein from more places, thus furthering the improvement of soybean peptide's conversion, so as to getting soybean meal feedstuffs of higher soybean peptide's conversion and nutrition richer. This thesis focuses on the following aspects. First, measure the targets such as the activity of protease and the conversion rate of soybean peptide in dynamic progress fermentation of Soybean meal, which was used for producing soybean meal feed by the effect of Bacillus subtilis1389, Aspergillus oryzae3.042, Aspergillus niger 3.350 as well as the preparation of Bacillus subtilis1389 and Aspergillus oryzae3.042 mixed, also Bacillus subtilis1389 and Aspergillus niger3.350. Second, make sure single factor conditions through the analysis of the dynamic fermentation results and do single factor experiments. Third, optimize the conditions of fermentation by doing orthogonal test.Changes of protease activities and soybean peptide's conversion rate are as follows in the course of dynamic ferment:Bacillus subtilis1389 and Aspergillus oryzae3.042 protease activities in the mixed fermentation: Protease activities gradually increased from 48 to 72 hours, and the maximum can reach in about 690U/g at 72h, after 72h protease activities gradually declined. Bacillus subtilis1389 and Aspergillus niger3.350 protease activities: protease activities gradually increased from 48 to 84 hours, and the maximum can reach in about 400U/g at 86h, after 86h protease activities gradually declined.Bacillus subtilis1389 and Aspergillus oryzae3.042 the conversion rate of soybean peptide in the mixed fermentation: soybean peptide's conversion rate gradually increased from 48 to 72 hours, and reached the maximum at 72h, after 72h the conversion rate of soybean peptide gradually declined and tended to balance. Bacillus subtilis1389 and Aspergillus niger3.350 soybean peptide's conversion rate in the mixed fermentation: soybean peptide's conversion rate gradually increased from 48 to 86 hours and reached the maximum at 86h, after 86h the conversion rate of soybean peptide gradually declinedA dynamic research based on single-factor test, and then by orthogonal testing from the view of protease activities and soybean peptide's conversion rate to determine the optimal ferment conditions:Under the conditions of fermentation for72h, the best fermentation conditions of Mixed-Culture Fermentation using Bacillus subtilis1389 and Aspergillus oryzae3.042 producing soybean meal feed were: inoculation time difference was 6h, the temperature of fermentation was 30℃, the medium moisture content was 64%, the ratio of inoculation was 1:1. The activity of protease measured was about 980U/g, while the conversion rate of soybean peptide was about 50% under these conditions. All of these were better than single-strain fermentation.Under the conditions of fermentation for 86h, the best fermentation conditions of Mixed-Culture Fermentation using Bacillus subtilis1389 and Aspergillus niger3.350 producing soybean meal feed were: inoculation time difference was 6h, the temperature of fermentation was 30℃, the medium moisture content was 64%, the ratio of inoculation was 1:2. The activity of protease measured was about 390U/g, while the conversion rate of soybean peptide was about 45% under these conditions. All of these were better than single-strain fermentation.