Abstract: This research aimed to screen for Lactobacillus strains with the capability of producing bacteriocin that can specifically inhibit foodborne pathogens and spoilage bacteria and to study the characteristics of the bacteriocin, so as to lay a foundation for its application in food preservation. Out of 112 isolates from pickles, one, coded Hlh32, was found able to produce bacteriocin (BacH32) and identified as Lactobacillus plantarum. The maximum production of BacH32 (anti-Staphylococcus aureus activity of 1 850 AU/mL) was achieved when the culture reached the stationary phase (between 18 and 24 h) in MRS broth at 35 ℃. The bacteriocin was purified sequentially by ammonium sulfate salting-out, DEAE Sepharose Fast Flow anion exchange chromatography, Sephadex G-15 gel filtration chromatography and reversed-phase HPLC. As determined by Trinice SDS-PAGE, the molecular mass of bacteriocin Hlh32 was 6.7 kDa, which was significantly different from that previously reported. It was sensitive to proteolytic enzymes but to lipase, α-amylase not β-amylase, indicating its protein nature. Its antimicrobial activity was maintained well after incubation for 4 h at pH 2–9, 30 min at 37, 60, 80 and 100 ℃, or 15 min at 121 ℃. The bacteriocin was found to have board-spectrum antimicrobial activity against both Gram-positive and Gram-negative bacteria together with fungi. BacH32 completely inhibited the growth of S. aureus cells at the early-log phase. These results indicate the potential of the bacteriocin for use as a food biopreservative.

Key words: Lactobacillus plantarum; bacteriocin; purification; antimicrobial characteristics