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1.
J Food Prot ; 75(8): 1501-6, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22856577

RESUMEN

The efficacy of depuration using UV light and chlorinated seawater for decontaminating Vibrio parahaemolyticus and Vibrio vulnificus from oysters was investigated. Oysters were contaminated with a five-strain cocktail of V. parahaemolyticus or V. vulnificus to levels of 10(4) to 10(5) CFU ml(-1) for bioaccumulation. The depuration was conducted in a closed system in which 350 liters of seawater was recirculated at a rate of 7 liters/min for 48 h at room temperature. Counts of V. parahaemolyticus or V. vulnificus were determined at 0, 6, 18, 24, and 48 h. Three treatments were conducted: T1, control treatment; T2, UV treatment; and T3, UV plus chlorine treatment. After 48 h of depuration of V. parahaemolyticus, T3 reduced the count by 3.1 log most probable number (MPN) g(-1) and T2 reduced the count by 2.4 log MPN g(-1), while T1 reduced the count by only 2.0 log MPN g(-1). After 48 h of depuration of V. vulnificus, T2 and T3 were efficient, reducing the counts by 2.5 and 2.4 log MPN g(-1), respectively, while T1 reduced the count by only 1.4 log MPN g(-1). The UV light plus chlorine treatment was more efficient for controlling V. parahaemolyticus in oysters. Both UV light and UV light plus chlorine were efficient for V. vulnificus. The present study is the first report showing the efficacy of depuration systems for decontaminating V. parahaemolyticus and V. vulnificus in oysters cultivated on the Brazilian coast. This study provides information on processes that can contribute to controlling and preventing such microorganisms in oysters and could be used for effective postharvest treatment by restaurants and small producers of oysters on the coast of Brazil.


Asunto(s)
Cloro/farmacología , Crassostrea/microbiología , Manipulación de Alimentos/métodos , Mariscos/microbiología , Rayos Ultravioleta , Vibrio parahaemolyticus/aislamiento & purificación , Vibrio vulnificus/aislamiento & purificación , Animales , Recuento de Colonia Microbiana , Seguridad de Productos para el Consumidor , Contaminación de Alimentos/análisis , Contaminación de Alimentos/prevención & control , Humanos , Agua de Mar , Vibrio parahaemolyticus/efectos de los fármacos , Vibrio parahaemolyticus/efectos de la radiación , Vibrio vulnificus/efectos de los fármacos , Vibrio vulnificus/efectos de la radiación
2.
Appl Environ Microbiol ; 75(6): 1697-702, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19151181

RESUMEN

The Vibrio parahaemolyticus O3:K6 pandemic clonal strain was first observed in southern Chile in 2004 and has since caused approximately 8,000 seafood-related diarrhea cases in this region. The massive proliferation of the original clonal population offers a unique opportunity to study the evolution of a bacterial pathogen in its natural environment by detection and characterization of emerging bacterial variants. Here, we describe a group of pandemic variants characterized by the presence of a 42-kb extrachromosomal DNA that can be recovered by alkaline extraction. Upon treatment with mitomycin C, these variants lyse with production of a myovirus containing DNA of equal size to the plasmid but which cannot be recovered by alkaline extraction. Plasmid and phage DNAs show similar restriction patterns corresponding to enzyme sites in a circular permutation. Sequenced regions showed 81 to 99% nucleotide similarity to bacteriophage VHML of Vibrio harveyi. Altogether these observations indicate that the 42-kb plasmid corresponds to a prophage, consisting of a linear DNA with terminal hairpins of a telomeric temperate phage with a linear genome. Bacteria containing the prophage were 7 to 15 times more sensitive to UV radiation, likely due to phage induction by UV irradiation as plasmid curing restored the original sensitivity. The enhanced UV sensitivity could have a significant role in reducing the survival and propagation capability of the V. parahaemolyticus pandemic strain in the ocean.


Asunto(s)
Bacteriófagos/fisiología , Viabilidad Microbiana/efectos de la radiación , Profagos/fisiología , Rayos Ultravioleta , Vibrio parahaemolyticus/efectos de la radiación , Vibrio parahaemolyticus/virología , Alquilantes/farmacología , Bacteriólisis , Bacteriófagos/genética , Chile , Enzimas de Restricción del ADN/metabolismo , ADN Viral/química , ADN Viral/genética , ADN Viral/metabolismo , Mitomicina/farmacología , Datos de Secuencia Molecular , Plásmidos , Profagos/genética , Mapeo Restrictivo , Análisis de Secuencia de ADN , Homología de Secuencia de Ácido Nucleico , Vibrio parahaemolyticus/genética , Virión/aislamiento & purificación , Virión/ultraestructura
3.
J Food Prot ; 66(6): 1025-9, 2003 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-12801004

RESUMEN

Irradiation is considered one of the most efficient technological processes for the reduction of microorganisms in food. It can be used to improve the safety of food products, and to extend their shelf lives. Oysters are considered one of the most important vehicles for pathogenic bacteria because of their feeding characteristics. The aim of this study was to evaluate the influence of a gamma radiation process on high levels of Salmonella Enteritidis, Salmonella Infantis, and Vibrio parahaemolyticus incorporated by oysters (Crassostrea brasiliana), as well as the effects of the process on the survival of the oysters and on their sensory attributes. The oysters were exposed to gamma radiation (60Co) in doses ranging from 0.5 to 3.0 kGy. A dose of 3.0 kGy was generally sufficient to reduce the level of Salmonella serotypes by 5 to 6 log10 units. A dose of 1.0 kGy was sufficient to produce a 6-log10 reduction in the level of V. parahaemolyticus. The highest irradiation dose did not kill the oysters or affect their sensory attributes. Hence, a dose of 3.0 kGy can be considered effective in inactivating Salmonella and V. parahaemolyticus in oysters without changing their odor, flavor, or appearance.


Asunto(s)
Irradiación de Alimentos , Ostreidae/microbiología , Salmonella/efectos de la radiación , Mariscos/microbiología , Vibrio parahaemolyticus/efectos de la radiación , Animales , Seguridad de Productos para el Consumidor , Relación Dosis-Respuesta en la Radiación , Conservación de Alimentos , Rayos gamma , Ostreidae/efectos de la radiación , Salmonella enteritidis/efectos de la radiación , Mariscos/efectos de la radiación , Mariscos/normas
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