89D-27 |
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K. YAMAZAKI, M. Minamikawa, T. Yamamoto, Y. Kawai, and N. Inoue. Graduate School of Fisheries Science, Hokkaido Univ., 3-1-1, Minato, Hakodate, 041-8611, Japan Bacteriocins are generally stable at high temperature and low pH, and show antimicrobial activity to gram-positive spore-formers. It might be suitable for inhibiting the growth of the thermoacidophilic spore-former, Alicyclobacillus, which is recognized as the most important target organisms in quality control of acidic drinks. We have recently isolated a bacteriocin-producing strain RB4 against the thermoacidophilic spore-formers. The objective of this study was to characterize a bacteriocin produced by strain RB4. Bacteriocin activity was measured by well-diffusion assay, and A.acidoterrestris ATCC49025 was used as an indicator strain for bacteriocin activity. The bacteriocin was purified to homogeneity by ammonium sulphate precipitation, cation exchange and reverse-phase HPLC chromatography. Strain RB4 was identified as Staphylococcus warneri by the morphological, biochemical characteristics and 16S rDNA sequence similarity. The supernatant of the strain RB4 culture showed a specific antibacterial activity against indicator strains of Alicyclobacilli and M.luteus, not against lactic acid bacteria, Staphylococcus, Listeria, Bacillus and gram-negative strains. The antibacterial activity was inactivated by trypsin and actinase E, but not by esterase, catalase, α-amylase or RNase. The bacteriocin activity of the supernatant was stable at 100o C for 15 min, and had a pH range of 2 to 6. The amino acid sequence, obtained by Edman degradation, was composed of a 27-amino acid residue. The amino acid sequence homology search revealed that this bacteriocin could be an identical or a closely related bacteriocin with Nukacin ISK-1. Molecular mass of the bacteriocin was estimated to be 2,958.2 Da by ESI-MS. The bacteriocin exhibited a bactericidal, and a bacteriolytic mode of action against indicator vegetative cells. From these properties, this bacteriocin produced by S. warneri RB4 might have the potential to ensure the quality of fruit juices and fruit juice-containing drinks.
Session 89D, Food Microbiology: Antimicrobial effects on foodborne microorganisms
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |