Screening of Bacillus with Antimicrobial Activity from Pickles and Physicochemical Characteristics of Bacteriocin

Objective:To screen Bacillus strain with antimicrobial activity from traditional fermented pickles. Methods:Bacillus strains with antimicrobial ability were double screened by heat treatment and bacterial culture plates. The strain was identified by biochemical tests and 16S rDNA sequence analysis. The antimicrobial activity substance from Bacillus was analyzed using protease sensitivity test,thermal treatment test and acid and alkaline test. Results:Strain PC-2 with outstanding antimicrobial activity from pickles was identified as Bacillus cereus. The cell-free supernatants from Bacillus was sensitive to papain,trypsin,prenase,but not to amylase and lipase. The antimicrobial activity to Escherichia coli and Streptomyces was stable after heat treatment 30 min with 70,80,90℃,and was effective within pH2.0~8.0. The cell-free supernatants from Bacillus PC-2 had broad spectrum of inhibition against Escherichia coli,Staphylococcus aureus,Saccharomycete and Streptomyces. Conclusion:Bacillus cereus PC-2 with strong antimicrobial activity against gram-positive bacterium and gram-negative bacterium was screened from fermented pickles. The antibacterial substance produced by strain PC-2 was preliminarily determined as bacteriocins. It lays the foundation for the development of new varieties of biological preservation.