| Summary: | Vibrio parahaemolyticus is the leading cause of foodborne illnesses associated with seafood consumption. Consuming raw or undercooked seafood contaminated with V. parahaemolyticus can result in development of acute gastroenteritis with symptoms of nausea, vomiting, abdominal cramping and watery diarrhea within 24 hours of infection. Illness is usually self-limited and lasts for about 3 days. The United States Centers for Disease Control and Prevention estimated that 45,000 cases of V. parahaemolyticus occur annually in the U.S. Depuration is a process which holds shellfish in clean seawater to allow them to purge sand and bacteria. Recently, we developed a refrigerated seawater (7 to 15 °C) depuration capable of decreasing V. parahaemolyticus populations in oysters by >3.0 log MPN/g after 5 days of the process with no adverse effect on oysters. However, the process needs to be shorted to allow application by the shellfish industry. This study investigated the bactericidal activity of natural antimicrobial substances, including rosemary, marjoram, clove, and grape seed extract, against five clinical V. parahaemolyticus strains (10290, 10292, 10293, BE 98-2029, O27-1c1) for their potential applications in depuration to increase its efficacy in reducing V. parahaemolyticus populations in contaminated oysters. Marjoram and rosemary contain low levels of phenolic compounds and had very little antimicrobial activity against V. parahaemolyticus. However, clove and grape seed extract exhibited strong bactericidal effects against clinical strains of V. parahaemolyticus. Populations of V. parahaemolyticus in tryptic soy broth supplemented with 1.5% NaCl (TSB-salt) containing 1.5% clove extract decreased rapidly by >3.88 - >4.81 log CFU/ml within 1 h of incubation at 37 °C. Similarly, populations of V. parahaemolyticus in TSB-salt containing 1% grape seed extract all declined to non-detectable (>4.69-log reductions) after 2 h. Further studies confirmed that both 1.5% of clove extract and 1.0% grade seed extract ...
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