Isolation and characterisation of the bacteriocin‐producingLeuconostoc citreumHW02from malts

Abstract

SummaryHerein, a lactic acid bacterium which produces bacteriocin was isolated from malted barley. The isolated strain was identified by 16 S rRNA analysis and designatedLeuconostoc citreumHW02. Bacteriocin HW02 was shown to have growth inhibition against health‐threatening Gram‐positive microorganisms such asStaphylococcus aureus,Listeria monocytogenes, andLatilactobacillus curvatus. Bacteriocin HW02 was reported to be incapable of inhibiting the growth of health‐threatening microorganisms after treatment with proteolytic enzymes; thus, it was indicated that bacteriocin is proteinaceous in nature. Bacteriocin HW02 showed stability against a broad range of temperatures (60–121 °C), pH (2–10), various detergents, or organic solvents. Its antimicrobial activity against the indicator strain,Lactiplantibacillus plantarumNCDO 955, was maximised (320 AU mL−1) midway through the stationary phase at 12 h. The crude bacteriocin HW02 molecular weight was estimated to be about 7.7 kDa. After the treatment of the indicator strain with bacteriocin, the maintenance of the optical density of the culture, the morphological analysis of cell‐structure abnormalities, and cell shrinkage implied that bacteriocin showed bactericidal activity.