A novel bacteriocin-producing strain, Lactobacillus plantarum JY22 isolated from golden carp intestine, was screened and identified by its physiobiochemical characteristics and 16S rRNA gene sequence analysis. This bacteriocin, named plantaricin JY22, was purified using ethyl acetate extraction and gel filtration. Its molecular weight was approximately 4.1 kDa by SDS-PAGE analysis. The partial amino acid sequence of plantaricin JY22 was DFGFDIPDEV. It was highly heat-stable and remained active at pH range from 2.5 to 5.5, but was sensitive to protease. Plantaricin JY22 had a bactericidal mode. Scanning electron microscope analysis indicated that plantaricin JY22 damaged the morphology of cells and spores for Bacillus cereus. Moreover, the plantaricin JY22 destroyed cell membrane integrity as confirmed by the leakage of electrolytes, the losses of Na+K+-ATP, AKP, nucleic acids (OD260nm) and proteins. SDS-PAGE of B. cereus proteins further demonstrated that plantaricin JY22 had a remarkable effect on bacterial proteins.
Keywords: Action mechanism; Bacillus cereus; Bacteriocin; Lactobacillus plantarum; Purification and characterization.