Abstract:

The aim is to obtain the fermentation strains with remarkable ability to produce enzyme and antibacterial property, and provide reference for the conversion of new feed resources and the search for antibiotic substitutes. Using strain H14 as the starting point, its enzymatic property and antibacterial ability were analyzed. The feed addition and fermentation time of fermented rapeseed meal were optimized by single factor experiments. A strain of Bacillus cereus H14 that produces cellulase, protease, amylase, and xylanase was screened and identified. The optimal reaction conditions for cellulase production were 60℃ and pH 9, and the activity of cellulase, protease, amylase and xylanase was 11.51 U/mL, 73.68 U/mL, 5.96 U/mL and 14.02 U/mL respectively. The maximum inhibitory diameters against Escherichia coli and Staphylococcus aureus were 18.200±0.200 mm and 17.567±0.493 mm, respectively. The optimal conditions for fermenting rapeseed meal to produce cellulase were adding 25% rapeseed, incubating for 48 h, enzyme activity reached 12.608 U/mL, and the optimal antibacterial effects on Escherichia coli and Staphylococcus aureus were adding 25% rapeseed meal and incubating for 48 h, the antibacterial diameter (mm) was 24.933±0.204; and adding 25% rapeseed meal and incubating for 72 h, the antibacterial diameter (mm) was 27.400±0.529, respectively. The fermentation products contain sucrose, xylose, and glucose. This experiment screened out a good fermentation strain, which could provide some reference for the development of fermented feed.

Key words: Bacillus cereus, screening and identification, senzymatic characteristic analysis, fermented rapeseed meal, antibacterial property, fermentation strain, cellulase, protease, amylase, xylanase, conversion of feed resources, alternative to antibiotics