Isolation,Identification and Biological Characteristics of Protease-Producing Bacillus subtilis from Bian Chicken
The purpose of this experiment was to screen probiotic with high protease-producing capacity and to expand the candidate strain resources of microecological agents.In this experiment,16 protease-producing strains were obtained by plate screening of skimmed milk using the rectal contents of Bian chickens as the isolation source,and after rescreened of liquid fermentation,one strain named FRE76 with a protease activity of 119.7 U/mL was selected for further study.Based on the 16S rRNA gene sequencing and evolutionary tree analysis,combined with morphological and physiological and biochemical identification,the strain was identified as Bacillus subtilis.The pathogens inhibition test showed that Bacillus subtilis had a significant inhibitory effect on both Escherichia coli and Staphylococcus aureus.Acid and bile salt resistance tests showed that the survival rate of this strain was more than 50％at pH 3.0 and 4.0,and the survival rate of the strain could reach more than 60％at bile salt concentrations of 0.1％and 0.3％.In summary,it can be found that Bacillus subtilis FRE76 screened in this experiment possessed excellent property for protease production,good inhibitory ability of pathogens and strong stress resistance,and is a potential probiotic strain.
probioticsBacillus subtilisisolation and identificationproteasebiological characteristics
万方数据
维普
