A fast method for monitoring the colonization rate of lactobacilli in a meat model system

A random amplified polymorphic DNA (RAPD) assay coupled to a fast and repro ducible cell lysis method from Lactobacillus colonies were developed to typ e lactobacilli of different strains and species, with the aim of precisely enumerating each of the different Lactobacillus strains inoculated in a nut rient-rich environment, such as sausage meat batter. Colonization assays we re carried out in an aseptic meat fermentation system for up to 14 d and th e inoculated strains were challenged with mixtures of wild lactobacilli. Th e proportion of inoculated strains remaining at different times was compare d with the total number of lactobacilli grown on MRS agar by RAPD. The colo nization rate of the different strains tested was very different. The RAPD- fast lysis method developed is simple and, with a low cost per assay, could also be applied to other food fermentations.