BACTERIOCINS OF Lactobacillus LF221 STRAIN

Abstract

LF221 strain is a Lactobacillus isolate from a baby’s faeces that was previously found to produce bacteriocin(s) with inhibitory activity against a wide range of bacterial species including some pathogenic and food-spoilage (Bacillus cereus, Clostridium sp., Listeria innocua, Staphylococcus aureus). Isoelectric point and molecular mass of bacteriocin complex and subunits were estimated. Precipitation with ammonium sulphate, cation exchange chromatography, C₈ hydrophobic interaction chromatography and reverse-phase FPLC chromatography were used to isolate bacteriocins from the supernatant of MRS culture. Amino acid composition and partial N-terminal amino acid sequences of two isolated bacteriocins were determined. Bacteriocins were present in MRS supernatant as aggregates with Mw>150.000 and pI 5.1-5.3, while Mw of subunits was 3500-5000. A high content of glycin and alanin was observed for both bacteriocins. The N-terminal amino acid sequences showed little similarity with those of other bacteriocins. Acidocins LF221 A and B appear to belong to the II class of LAB bacteriocins.