Ascorbic acid-induced loss of a pediocin-encoding plasmid in Pediococcus acidilactici CFR K7

A strain of Pediococcus acidilactici CFR K7 grown in presence of 1 mm ascor bate for 18 h resulted in 35% colony-forming units (CFU) irreversibly losin g their ability to produce pediocin. Agarose gel electrophoresis of plasmid DNA and dot-blot hybridization showed concomitant loss of a 7.8 kb plasmid coding for pediocin from these colonies. Sensitivity of these colonies to nitrofurantoin was also observed after ascorbate treatment. Since ascorbic acid is a readily available and non-hazardous compound in contrast to other conventional plasmid curing agents, the possibility of its use in determin ing plasmid-encoded traits in food grade lactic acid bacteria is also propo sed.