SPECIFIC DETECTION OF A PROBIOTIC LACTOBACILLUS STRAIN IN FECAL SAMPLES BY USING MULTIPLEX PCR

Lactobacillus gasseri 4B2 is a human isolate characterised by a strong autoaggregating phenotype mediated by APF (aggregation-promoting fact or), a secreted protein. Two primer pairs were developed for simultane ous amplification of a specific fragment of the APF gene and a highly conserved region of the 16S rRNA gene. The specificity of this protoco l was checked in DNA samples isolated from single and mixed cultures o f Lactobacillus. The same amplification protocol was successfully used directly adding whole bacterial cells to PCR reaction tubes. The suit ability of this method for in vivo studies was investigated through fe eding L. gasseri 4B2 to mice and analysing colony forming units obtain ed by plating faecal samples on selective medium. The methodology allo ws a fast and reliable identification of the target strain without any DNA extraction procedure. (C) 1998 Federation of European Microbiolog ical Societies. Published by Elsevier Science B.V.