Identification of Vibrio proteolyticus with a differential medium and a specific probe

A differential medium (VP8) and a specific probe, based on the variable region V3 of the 16S rRNA gene, for the detection of Vibrio proteolyticus are defined. The medium contains 8% NaCl, which allows selective growth of moderately halophilic Vibrio strains. D-Sorbitol, as the main carbon source, differentiates the species that can ferment it by the pH indicators cresol red and bromothymol blue. V. proteolyticus and 8 of 418 strains studied grew on the medium and used the D-sorbitol, forming bright yellow colonies. An oligonucleotide, based on the variable region V3 of the 16S rRNA gene (5'CGCTAACGTCAAATAATGCATCTA3'), was used as the specific probe (V3VPR). Only three strains of Vibrio sp. and one strain identified as V. natriegens cross-hybridized with the probe. However, unlike V. proteolyticus, none of the strains grew on VP8. The combined use of VP8 medium and the probe allowed an unequivocal identification of V. proteolyticus.