Application of a molecular beacon-real-time PCR technology to detect Salmonella species contaminating fruits and vegetables.
An oligonucleotide probe that becomes fluorescent upon hybridization to the target DNA (molecular beacon; MB) was evaluated in a real-time polymerase chain reaction (PCR) assay to detect the presence of Salmonella species. As few as 1-4 colony-forming units (CFU) per PCR reaction could be detected. The capability of the assay to detect Salmonella species from artificially inoculated fresh-cut produce such as cantaloupe, mixed-salad, cilantro, and alfalfa sprouts was demonstrated. A comparison of two commercially available kits utilizing MB-PCR (iQ-Check, Bio-Rad Laboratories) and conventional Association of Official Analytical Chemists (AOAC)-approved PCR (BAX, Dupont Qualicon) was performed on artificially inoculated produce. As few as 4 CFU/25 g of produce were detected after 16 h of enrichment in buffered peptone broth. These assays could be carried out entirely in sealed PCR tubes, enabling a rapid and high-throughput detection of Salmonella species in a large number of food and environmental samples. This is the first report of the application of MB probe being used for real-time detection of Salmonella species in whole and fresh-cut fruits and vegetables.
Produce Quality and Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, 10300 Baltimore Avenue, Building 002, Room 117, BARC-W, Beltsville, MD 20705-2350, USA.
Samantha Hu
SH
Liming
Arvind A
AA
Bhagwat
D015169:Colony Count, Microbial; D005453:Fluorescence; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D005638:Fruit / Q000382:microbiology*; D005798:Genes, Bacterial; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction / Q000379:methods*; D012475:Salmonella / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D014675:Vegetables / Q000382:microbiology*
D015345:Oligonucleotide Probes