APPLICATION OF RANDOM AMPLIFIED POLYMORPHIC DNA ANALYSIS FOR DETECTION OF SALMONELLA SPP. IN FOODS

The random amplified polymorphic DNA (RAPD) band patterns from 23 Salm onella spp. produced by use of an oligonucleotide primer (called du pr imer) designed on the basis of the N-terminal sequence of dulcitol I-p hosphate dehydrogenase (5'-GTGGTGACCCAGGATGGCCAGGTG-3') were different from those from 16 non-Salmonella spp. The bands at 460 and 700 bp we re produced in all Salmonella strains tested. These RAPD fragments obt ained from Salmonella typhimurium strongly hybridized with the corresp onding RAPD bands from the other strains of Salmonella, but not with t hose from non-Salmonella spp. in Southern blot analysis. The:RAPD band s were detected by ethidium bromide staining even when genomic DNA pre pared from as few as 2.8 x 10(3) cells was used. The minimum detectabl e cell number in the initial inoculum of S. typhimurium was 4 x 10(-1) CFU/25 g of raw beef after the preenrichment in Enterobacteriaceae en richment mannitol (EEM) broth for 6 h and the selective enrichment in dulcitol-magnesium chloride-pyridinesulfonic acid-brilliant green-novo biocin (DMPBN) medium for 18 h at 42 degrees C. Seven raw foods inocul ated with S. typhimurium at numbers from 4 x 10(-1) to 2.6 x 10(2) CFU /25 g of food were positive in both the RAPD analysis and the conventi onal culture method.