Isolation and preliminary characterization of Lactobacillus plantarum bacteriophages from table olive fermentation

Abstract

Nine table olive fermentation brines were analysed to demonstrate the presence of lytic bacteriophages active against Lactobacillus plantarum strains. Five brines, out of the nine studied, were added to selected strains of L. plantarum as starter cultures, while the other four brines were left to ferment spontaneously. Turbidity tests with different host strains inoculated in growth medium with added filter-sterilized brines demonstrated the presence of phages able to lyse the sensitive strains. Phages were isolated from fermented brines and their presence was confirmed by scanning electron microscopy. A subsequent phage characterization based on host range, restriction analysis and protein profiles was performed. This study reported for the first time the isolation and characterization of L. plantarum phages from table olive fermentation. This demonstrated presence of lytic phages active against L. plantarum could represent a serious obstacle in the regular table olive fermentation process. For these reasons, the search for phage-resistant strains, to use as starter cultures, could be important to counteract the development of fermentation problems.