Persistent Vibrio-parahaemolyticus-associated vibriosis cases, attributed, in part, to the inefficient techniques for detecting viable-but-non-culturable (VBNC) Vibrio pathogens and the ingestion of undercooked seafood, is the leading cause of bacterial seafood-borne outbreaks, hospitalizations, and deaths in the United States. The effect of extreme heat processing on Vibrio biology and its potential food safety implication has been underexplored. In the present work, environmental samples from the wet market, lagoon, and estuarine environments were analyzed for V. parahaemolyticus recovery using a modified, temperature-dependent, two-step enrichment method followed by culture-based isolation, phenotype, and genotype characterizations. The work recovered novel strains (30% of 12 isolates) of V. parahaemolyticus from prolonged-heat-processing conditions (80 °C, 20 min), as confirmed by 16S rDNA bacterial identification. Select strains, VHT1 and VHT2, were determined to be hemolysis- and urease-positive pathogens. PCR analyses of chromosomal DNA implicated the tdh-independent, tlh-associated hemolysis in these strains. Both strains exhibited significant, diverse antibiotic profiles (p < 0.05). Turbidimetric and viable count assays revealed the pasteurization-resistant V. parahaemolyticus VHT1/VHT2 (62 °C, 8 h). These findings disclose the efficiency of Vibrio extremist recovery by the modified, two-step enrichment technique and improve knowledge of Vibrio biology essential to food safety reformation.
Keywords: Vibrio parahaemolyticus; foodborne pathogen; heat-resistant; pasteurization; safety; seafood; spore; viable-but-non-culturable (VBNC); vibriosis.