title: Improved fluorogenic assay for rapid detection of Vibrio parahaemolyticus in foods.
abstract: An improved fluorogenic assay for the rapid detection of Vibrio parahaemolyticus was developed. In the improved assay, the enrichment of V. parahaemolyticus was carried out in arabinose-glucuronate medium (0.5% arabinose, 0.25% glucuronate, 0.1% polypeptone, 0.1% yeast extract, 0.1% ammonium sulfate, 2% NaCl, 2 micrograms of polymyxin B sulfate per ml, pH 8.5) at 37 degrees C. After the cultivation, the trypsinlike activity of the bacteria was measured by fluorescence with the fluorogenic substrate benzoyl-L-arginine-7-aminomethylcoumarin. Even in the presence of 3 x 10(5) cells of Vibrio alginolyticus, 20 cells of V. parahaemolyticus were clearly detected after a 6-h enrichment cultivation by the assay. Fifty contaminated samples of 14 seafoods were examined for V. parahaemolyticus by the fluorogenic assay after enrichment cultivation for 6 or 8 h. The results were then compared with those obtained by the conventional bromothymol blue Teepol agar assay and the most-probable-number method. There was a linear relationship between trypsinlike activity measured by the assay and the number of V. parahaemolyticus cells in seafood as determined by the bromothymol blue Teepol agar and most-probable-number methods. Correlation coefficients were 0.95 and 0.93 after a 6-h cultivation and an 8-h cultivation, respectively. The presence of 10 cells of V. parahaemolyticus per gram of seafood sample was detected after a 10-h total detection time by the fluorogenic assay.
authors.affiliation: Department of Food Science and Technology, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Miyamoto
authors.forename: H
authors.initials: H
authors.lastname: Miwa
authors.forename: S
authors.initials: S
authors.lastname: Hatano
mesh_terms: D000818:Animals; D003470:Culture Media; D033364:Decapoda / Q000382:microbiology; D005399:Fishes / Q000382:microbiology; D005516:Food Microbiology; D014357:Trypsin / Q000032:analysis; D014736:Vibrio parahaemolyticus / Q000254:growth & development / Q000302:isolation & purification*
chemical_list: D003470:Culture Media; D014357:Trypsin