Plasmid DNA studies in Lactobacillus plantarum strains isolated from olive fermentations:production of and immunity to plantaricin OL15 is associated to a 9.6 Kb plasmid(pOL15)

摘要

Previously 12 Lactobacillus plantarum strains were isolated from fermented olives.Among these,only L.plantarum OL15 produced bacteriocin(plantaricin OL15).In this study,the 12 strains were examined for plasmid DNA content.Of these,9 strains have shown one to three plasmid bands ranging in size from 5.4 to 12.2 kb.L.plantarum OL15 exhibited one plasmid(9.6 kb)which was named pOL15.After curing with novobiocin and ethidium bromide,the plasmid profile analysis of non producing derivatives,showed that the 9.6 kb plasmid pOL15 harbored by the parental strain had been lost in all cases and none of them regained the ability to produce plantaricin OL15 suggesting that the production of plantaricin OL15 is plasmid linked.' Plantaricin OL15 was not inactived by amylase and lipase suggesting that plantaricin OL15 activity was not dependent on the presence of either a carbohydrate or lipid moiety.Plantaricin OL15 showed activity against lactic acid bacteria of different species and also against olive spoilage and phytopathogenic bacteria,including Pseudomonas and Erwinia.