ABSTRACT
A new bacteriocin, lacticin LC14, produced by Lactococcus lactis BMG6.14, was isolated and characterized. It was purified to homogeneity from overnight broth culture by ammonium sulfate precipitation, Sep-Pak chromatography, and two steps of reversed-phase HPLC. Lacticin LC14 showed bactericidal-type antimicrobial activity against several lactic acid bacteria and pathogenic strains including Listeria monocytogenes. It was inactivated by proteinase K and pronase E, but was resistant to papain, lysozyme, lipase and catalase. Lacticin LC14 was heat resistant, stable over a wide range of pH (2-10) and after treatment by solvents and detergents. Its N-terminal end was found unreactive towards Edman sequencing. Based on MALDI-TOF mass spectrometry, its molecular mass was 3333.7 Da. LC14 amino acid composition revealed a high proportion of hydrophobic residues, but no modified ones. LC14 may be able to challenge other well known other bacteriocins in probiotic and therapeutic applications.
Subject(s)
Bacteriocins/isolation & purification , Lactococcus lactis/metabolism , Amino Acid Sequence , Amino Acids/analysis , Bacteriocins/analysis , Bacteriocins/chemistry , Bacteriocins/pharmacology , Lactococcus lactis/isolation & purificationABSTRACT
Bacteriocin J46 is a 27-residue polypeptide produced by Lactococcus lactis subsp. cremoris J46 in fermented milk. The natural form of J46 (nJ46) exhibits a broad antimicrobial spectrum. Herein, we produced the synthetic form of J46 (sJ46) by solid-phase chemical synthesis. The biochemical and physico-chemical properties of sJ46, as well as its antimicrobial activity, were found to be identical to those of its natural counterpart nJ46. It showed a potent antimicrobial activity against both lactic acid bacteria and other Gram-positive microorganisms. (1)H-NMR conformational analysis of sJ46 indicates that it adopts a flexible random coil structure.
