Study On Preparation Of Bioactive Feed From By-products Of Soybean Fermented Soybean Processing By Compound Bacteria

Soybean hulls and protein residues,as by-products of soybean processing,not only have a large output,but also are rich in nutrients,and a more appropriate resource disposal method is used as feed materials.However,the macromolecular protein and fiber components are difficult for livestock and pouitry to use directly.After microbial fermentation treatment,it can be transformed into high-quality protein-based feed,alleviating the shortage of feed in my country,while creating economic value and reducing environmental pressure.In this project,Bacillus subtilis B5,Candida utilis Y6 and Bacillus megaterium mutant B18-2 were used for solid-state fermentation of soybean processing by-products,and the mixed bacterial solid-state fermentation was carried out using the optimized process parameters of single-bacteria fermentation.In order to obtain feed products with high protease activity and high cellulase activity.First,in order to improve the cellulase activity of Bacillus megaterium B18,the conditions of He-Ne laser mutagenesis were studied,and the mutants with the highest cellulase activity were selected based on the indicators of the size of the hydrolysis circle,positive mutation rate and lethality..The results showed that the optimal dose of He-Ne laser mutagenization of B18 was 15mW for 10min.The optimal mutant B18-2 had a 57.3%increase in cellulase activity compared to the original strain B18,and had good genetic stability.Simultaneously,the fermentation conditions of single bacteria of Bacillus subtilis,Candida utilis and Bacillus megaterium mutants were studied,with protease activity,cell concentration and cellulase activity as indicators.the result shows:(1)Bacillus subtilis was cultured at 32? for 52h,with an inoculation volume of 3%,a loading volume of 25g,a water content of 60%,and a urea addition of 1.5%.The protease activity was the highest,reaching 613.8U/g.(2)Candida utilis was cultured at 30? for 28 hours,with a 100 mL filling volume,11%inoculation volume,and 1.5%peptone addition,the highest bacterial concentration.(3)Mutant strain B18-2 was cultured at 32? for 40h,with a loading volume of 20g,an inoculation volume of 3%,a water content of 55%,and an ammonium sulfate addition of 1.5%.The cellulase activity was the highest,up to 139.6U/g.Then the optimization test of the mixed-bacteria solid-state fermentation process was carried out,and the fermentation temperature,charging amount and water content in the fermentation parameters were optimized by response surface method.the result shows:(1)The best fermentation combination is Bacillus subtilis,Candida utilis and Bacillus megaterium mutant strain B18-2,the inoculation ratio is 3%:1%:2%,and the best conditions for the solid state fermentation of the bacteria are:soybean hulls The mass ratio of dry protein residue to wet protein residue is 1:1:2,the loading amount is 22g,the amount of urea added is 1.5%,the water content is 58%,and cultured at 30? for 48h.(2)Finally,the conditions were corrected to fermentation temperature 31°C.,charging amount 22 g,and water content 58%.The average protease activity was 881.5 U/g,and the average cellulase activity was 196.6 U/g.Through the pilot test,the crude protein content of the fermentation product was determined to be about 29%,which was an increase of 6%-7%compared to before fermentation;the crude fiber content was about 12%,which was decreased by 3%-4%compared to before fermentation.It also meets industry standards.Finally,through broiler feeding experiments,the effects of fermentation products on the death rate,production performance,carcass performance,immune organ index,and meat quality index were studied.The results showed that the death rate of the test group with 10%fermentation product was 2%1 ower than that of the control group,the average daily feed intake was 6g more than that of the control group,the average daily weight gain was 7.1g higher than that of the control group,and the feed ratio also decreased.At the same time,the carcass quality,immune organ index and meat quality index of broilers in the experimental group have improved,indicating that adding a certain amount of fermentation products can promote broiler eating,enhance immunity,and improve intestinal health.