Study On The Characteristics And Antibacterial Activity Of A Bacillus Amyloliquefaciens

Bacillus amylus can produce many enzymes to help animals digest feed and secondary metabolites can inhibit pathogens.In this experiment,the growth curve,acid resistance,bile salt resistance and enzyme production of a strain of Bacillus amyloliquefaciens Y1 from a bovine rumen source were studied.And the antibacterial of the fermentation products and the stability of the antibacterial substances were determined.The growth curve of Bacillus amyloliquefaciens Y1 was determined by growth rate method.The characteristics of acid tolerance and bile salt tolerance were determined by viable count method.The enzyme activity and thermal stability of amylase and cellulase were determined by 3,5-two nitrosalicylic acid(DNS)method.The bacteria of Escherichia coli,Vibrio parahemolyticus,Sarcina lutea and Aerogenes,and Aspergillus niger and Rhizopus nigricans were used as indicative bacteria.The Oxford cup method was used to measure.The stability and antibacterial activity of the antibacterial substances were determined.The experimental results show that,Bacillus amyloliquefaciens Y1 at 37?,180 r/min,in broth medium,4-24 hours for its logarithmic growth period,after 24 hours to have a large number of spores,30 hours all spore.The characteristics of Bacillus amyloliquefaciens Y1 were studied.It was found that Y1 had good acid resistance,bile salt and other characteristics.The survival rate of pH 3 and 6 was 32.9% and 97.6% respectively,and the survival rate was64.2% in the bile salt with the concentration of 0.4%.After 20 h culture,the amylase activity reached 20.26 U\mol and cellulase activity reached 8.98 U\mol.Compared with the 25?enzyme activity,the amylase and cellulase maintained high activity at 80 and reached 72.2%and 77.8% respectively,indicating that the two enzymes had better thermal stability.Through the bacteriostasis experiment,it was found that the fermented product of Bacillus amyloid had certain bacteriostasis effect on the selected indicator bacteria.Among them,the bacteriostasis effect on bacterial Escherichia coli was best to reach 39.75 mm,and the best bacteriostatic effect of Aspergillus niger was 17.30 mm.The bacteriostat in the fermented product has good stability of acid base,thermal stability and protease stability.The antibacterial activity of neutral protease and flavor protease is still 75.3% and 80.1% after treatment.