Preliminary Study On A Strain Of Bacillus Pumilus Used For Solid Fermentation Of Soybean Meal And Prevention Of Bacterial Diarrhea

This study screened and identified multiple strains of protease-producing bacteria from80 soils.From this,Bacillus pumilus(A9)was selected for solid-state fermentation of soybean meal,and the fermentation conditions were optimized.The effect of fermented soybean meal instead of soybean meal in the diet on the growth of mice and the comparison of the therapeutic effect on diarrhea caused by Escherichia coli and Salmonella were verified.Firstly,skim milk powder was used as the medium substrate for the initial screening,combined with the three aspects of protease production capacity,morphology and molecular biology to determine Pseudomonas aeruginosa A8,Bacillus pumilus A9 and Haemophilus A25 A strain with strong enzyme capacity.By comparing the ratio of the diameter of the transparent circle to the diameter of the colony(H/C value)and the ability to produce enzymes,Bacillus pumilus A9 was selected for solid-state fermentation.By optimizing the three main conditions of the initial moisture content,fermentation time and inoculation volume of Bacillus pumilus solid-state fermentation soybean meal.The best solution was determined as follows: the optimal initial water content was 80%,the optimal fermentation time was 120 h,and the optimal inoculation volume was 10%.Through the heat resistance test of B.brevis,the drying temperature of the fermented soybean meal was determined to be 40°C.Isolate and identify Escherichia coli and Salmonella from the intestines of sick pigs,and then infuse mice with Escherichia coli and Salmonella to establish a mouse diarrhea model.Compared with control mice,the experimental mice fed with Bacillus pumilus A9 fermented soybean meal had significantly reduced diarrhea symptoms and shortened duration of diarrhea.Tests have shown that Bacillus pumilus A9 fermented soybean meal has good prevention and treatment effects on diarrhea in mice,and is expected to be developed as a functional feed for preventing bacterial diarrhea in weaned piglets.