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1.
Halophilic Bdellovibrio, which is parasitic and lytic to Vibrio pharahaemolyticus, was ioslated from fresh sea water in the winter. It had a lethal effect on V. parahaemolyticus. The optimum temperature ofr multiplication ranged from 25 C to 30 C and growth was not observed at 35 C. Plaque numbers of the isolate reached a maximum in 17 hr under conditions of shaking at 25 C in autoclaved sea water supplemented with V. parahaemolyticus cells, and were as high as ten times the number of host cells. With respect to the host-suspended medium, the isolate multiplied in natural sea water ten times more than in Herbst's artificial sea water but did not grow in saline. V. parahaemolyticus, Vibrio alginolyticus and several species in the Vibrio genus were susceptible to the parasite on the basis of plaque formation but Escherichia coli and Staphylococcus aureus were not. 相似文献
2.
Mingkwan Yingkajorn Natthawan Sermwitayawong Prasit Palittapongarnpimp Mitsuaki Nishibuchi William P. Robins John J. Mekalanos Varaporn Vuddhakul 《Microbial ecology》2014,67(4):849-856
Correlation between the numbers of Vibrio parahaemolyticus and its specific bacteriophages in cockles was investigated from June 2009 to May 2010 in Hat Yai, Songkhla, Thailand. Cockles obtained monthly from a local market were sampled to determine the numbers of V. parahaemolyticus and bacteriophages that could form plaques on ten strains of pandemic and nonpandemic V. parahaemolyticus. In addition, V. parahaemolyticus isolates from clinical samples from Hat Yai hospital over the same period were investigated. All 139 cockles sampled were positive for V. parahaemolyticus. However, only 76 of them were positive for bacteriophages. During the testing period, the number of bacteriophages was not significantly correlated with the incidence of V. parahaemolyticus-infected patients, but the numbers of V. parahaemolyticus isolates from the cockle samples were closely related to the number of infected patients. The bacteriophages isolated from V. parahaemolyticus also infected Vibrio alginolyticus and Vibrio mimicus, suggesting that the broad host range of phages may be a factor of providing the possibility of their participation in the processes of genetic exchange between V. parahaemolyticus and closely related Vibrio spp. In conclusion, this study indicated that the number of V. parahaemolyticus in cockles may be a useful tool for predicting the relative risk of infection by V. parahaemolyticus in this area of Thailand. 相似文献
3.
A highly sensitive and specific multiplex PCR assay for simultaneous detection of Vibrio cholerae,Vibrio parahaemolyticus and Vibrio vulnificus 总被引:1,自引:0,他引:1
S.B. Neogi N. Chowdhury M. Asakura A. Hinenoya S. Haldar S.M. Saidi K. Kogure R.J. Lara S. Yamasaki 《Letters in applied microbiology》2010,51(3):293-300
Aims: To develop an effective multiplex PCR for simultaneous and rapid detection of Vibrio cholerae, Vibrio vulnificus and Vibrio parahaemolyticus, the three most important Vibrio species that can cause devastating health hazards among human. Methods and Results: Species‐specific PCR primers were designed based on toxR gene for V. cholerae and V. parahaemolyticus, and vvhA gene for V. vulnificus. The multiplex PCR was validated with 488 Vibrio strains including 322 V. cholerae, 12 V. vulnificus, and 82 V. parahaemolyticus, 20 other Vibrio species and 17 other bacterial species associated with human diseases. It could detect the three target bacteria without any ambiguity even among closely related species. It showed good efficiency in detection of co‐existing target species in the same sample. The detection limit of all the target species was ten cells per PCR tube. Conclusions: Specificity and sensitivity of the multiplex PCR is 100% each and sufficient for simultaneous detection of these potentially pathogenic Vibrio species in clinical and environmental samples. Significance and Impact of the Study: This simple, rapid and cost‐effective method can be applicable in a prediction system to prevent disease outbreak by these Vibrio species and can be considered as an effective tool for both epidemiologist and ecologist. 相似文献
4.
Chen W Yu S Zhang C Zhang J Shi C Hu Y Suo B Cao H Shi X 《Applied microbiology and biotechnology》2011,89(6):1979-1990
In this study, a single base extension-tag array on glass slides (SBE-TAGS) microarray was established to detect the seven
leading seafood-borne pathogens, including Vibrio parahaemolyticus, Vibrio cholerae, Vibrio vulnificus, Vibrio mimicus, Vibrio alginolyticus, Vibrio anguillarum, and Vibrio harveyi. Three multiplex PCR assays were developed to specifically target the following species with individual gene markers, which
are aadS, tdh, and trh for V. parahaemolyticus; col, toxR, and vvh for V. alginolyticus, V. mimicus, and V. vulnificus; and empA, vhh1, and tcpA for V. anguillarum, V. harveyi, and V. cholerae, respectively. The purified PCR products were used as template DNA for single base extension-tag reactions, labeled with
Cy3 fluorescent dye and hybridized to DNA microarrays. The detection specificity of this microarray method was 100%, with
the sensitivity for pure genomic DNA at 200 fg to 2 pg per reaction. Application of the DNA microarray methodology to 55 naturally
contaminated seafood samples (shrimp, fish, and oysters) revealed the presence of V. parahaemolyticus at 50.9% and V. alginolyticus at 32.7%. This corresponds with traditional assays (microbiological and biochemical tests) except one sample which was identified
as negative in V. parahaemolyticus by the microarray assay but as positive by the conventional method. Therefore, a combination of multiplex PCR with DNA microarray
hybridization based on SBE-TAGS ensures rapid and accurate detection of pathogenic Vibrio species in seafood, thereby providing safer seafood products for consumers at a low financial burden to the aquaculture industry. 相似文献
5.
Vibrio parahaemolyticus, the flagellated nonswarming marine bacteria were induced to swarm on solid media under three different conditions: growth at 20–26°C on medium containing 1% NaCl, growth on a medium in a sealed Petridish and growth on H2O2-treated medium. The morphological transformations observed in cells during swarming of V. parahaemolyticus are similar to those found jor the naturally swarming Vibrio alginolyticus. The mechanism of swarming in both species involves massive formation of peritrichous flagella and a negative chemotactive response to metabolic byproducts. 相似文献
6.
Aim: To detect Aeromonas spp., Salmonella spp., Vibrio cholerae, Vibrio parahaemolyticus and Vibrio vulnificus in mussels and water samples from a farming area, conventional and molecular methods were applied to enrichment cultures. Methods and Results: The aerolysin gene (aero) of Aeromonas spp., the invasion plasmid antigen B (ipaB) gene of Salmonella spp., the enterotoxin secretion protein (epsM) gene of V. cholerae, the species‐specific region of 16S rRNA gene of V. vulnificus, the 16S–23S rDNA (IGS) gene of V. parahaemolyticus and the pR72H fragment of V. parahaemolyticus were amplified by multiplex polymerase chain reaction (PCR) assays on DNA extracted from enrichment cultures. The haemolysin gene (tdh) of pathogenic V. parahaemolyticus was also amplified. Conventional culture method allowed the isolation of V. parahaemolyticus and V. vulnificus from water and mussels. The genes aero, epsM and 16S rRNA of V. vulnificus were occasionally detected in the enrichment cultures. In mussels, the ipaB and IGS genes were detected from June to September and from April to November, respectively. All genes, except aero, were amplified from mussels collected in September, when pathogenic V. parahaemolyticus (tdh+) strains were also isolated. Conclusions: Multiplex‐PCR assays were more sensitive and faster than conventional procedures. Significance and Impact of the Study: The results emphasize the need of an accurate and rapid detection of bacterial pathogens in mussels to protect human health. 相似文献
7.
Simone I. Böer Ernst-August Heinemeyer Katrin Luden René Erler Gunnar Gerdts Frank Janssen Nicole Brennholt 《Microbial ecology》2013,65(4):1052-1067
The number of reported Vibrio-related wound infections associated with recreational bathing in Northern Europe has increased within the last decades. In order to study the health risk from potentially pathogenic Vibrio spp. in the central Wadden Sea, the seasonal and spatial distribution of Vibrio vulnificus, Vibrio parahaemolyticus, Vibrio alginolyticus and Vibrio cholerae were investigated at ten recreational beaches in this area over a 2-year period. V. alginolyticus and V. parahaemolyticus were found to be omnipresent all year round in the study area, while V. vulnificus occurrence was restricted to summer months in the estuaries of the rivers Ems and Weser. Multiple linear regression models revealed that water temperature is the most important determinant of Vibrio spp. occurrence in the area. Differentiated regression models showed a species-specific response to water temperature and revealed a particularly strong effect of even minor temperature increases on the probability of detecting V. vulnificus in summer. In sediments, Vibrio spp. concentrations were up to three orders of magnitude higher than in water. Also, V. alginolyticus and V. parahaemolyticus were found to be less susceptible towards winter temperatures in the benthic environment than in the water, indicating an important role of sediments for Vibrio ecology. While only a very small percentage of tested V. parahaemolyticus proved to be potentially pathogenic, the presence of V. vulnificus during the summer months should be regarded with care. 相似文献
8.
Savannah L. Klein Casandra K. Gutierrez West Diana M. Mejia Charles R. Lovell 《Applied and environmental microbiology》2014,80(2):595-602
Detection of the human pathogen Vibrio parahaemolyticus often relies on molecular biological analysis of species-specific virulence factor genes. These genes have been employed in determinations of V. parahaemolyticus population numbers and the prevalence of pathogenic V. parahaemolyticus strains. Strains of the Vibrionaceae species Photobacterium damselae, Vibrio diabolicus, Vibrio harveyi, and Vibrio natriegens, as well as strains similar to
Vibrio tubiashii, were isolated from a pristine salt marsh estuary. These strains were examined for the V. parahaemolyticus hemolysin genes tdh, trh, and tlh and for the V. parahaemolyticus type III secretion system 2α gene vscC2 using established PCR primers and protocols. Virulence-related genes occurred at high frequencies in non-V. parahaemolyticus Vibrionaceae species. V. diabolicus was of particular interest, as several strains were recovered, and the large majority (>83%) contained virulence-related genes. It is clear that detection of these genes does not ensure correct identification of virulent V. parahaemolyticus. Further, the occurrence of V. parahaemolyticus-like virulence factors in other vibrios potentially complicates tracking of outbreaks of V. parahaemolyticus infections. 相似文献
9.
S. Haldar S.B. Neogi K. Kogure S. Chatterjee N. Chowdhury A. Hinenoya M. Asakura S. Yamasaki 《Letters in applied microbiology》2010,50(2):146-152
Aim: To develop a haemolysin (hly) gene‐based species‐specific multiplex PCR for simple and rapid detection of Vibrio campbellii, V. harveyi and V. parahaemolyticus. Methods and Results: The complete hly genes of three V. campbellii strains isolated from diseased shrimps were sequenced and species‐specific PCR primers were designed based on these sequences and the registered hly gene sequences of Vibrio harveyi and Vibrio parahaemolyticus. Specificity and sensitivity of the multiplex PCR was validated with 27 V. campbellii, 16 V. harveyi, and 69 V. parahaemolyticus, 18 other Vibrio species, one Photobacterium damselae and nine other bacterial species. The detection limits of all the three target species were in between 10 and 100 cells per PCR tube. Conclusions: Specificity and sensitivity of the multiplex PCR is 100% each and sufficient to be considered as an effective tool in a prediction system to prevent potential disease outbreak by these Vibrio species. Significance and Impact of the Study: Because there is lack of simple, rapid and cost‐effective method to differentiate these closely related V. campbellii, V. harveyi and V. parahaemolyticus species, the multiplex PCR developed in this study will be very effective in epidemiological, ecological and economical points of view. 相似文献
10.
Miller WA Miller MA Gardner IA Atwill ER Byrne BA Jang S Harris M Ames J Jessup D Paradies D Worcester K Melli A Conrad PA 《Microbial ecology》2006,52(2):198-206
The coastal ecosystems of California are highly utilized by humans and animals, but the ecology of fecal bacteria at the land–sea interface is not well understood. This study evaluated the distribution of potentially pathogenic bacteria in invertebrates from linked marine, estuarine, and freshwater ecosystems in central California. A variety of filter-feeding clams, mussels, worms, and crab tissues were selectively cultured for Salmonella spp., Campylobacter spp., Escherichia coli-O157, Clostridium perfringens, Plesiomonas shigelloides, and Vibrio spp. A longitudinal study assessed environmental risk factors for detecting these bacterial species in sentinel mussel batches. Putative risk factors included mussel collection near higher risk areas for livestock or human sewage exposure, adjacent human population density, season, recent precipitation, water temperature, water type, bivalve type, and freshwater outflow exposure. Bacteria detected in invertebrates included Salmonella spp., C. perfringens, P. shigelloides, Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio alginolyticus. Overall, 80% of mussel batches were culture positive for at least one of the bacterial species, although the pathogens Campylobacter, E. coli-O157, and Salmonella were not detected. Many of the same bacterial species were also cultured from upstream estuarine and riverine invertebrates. Exposure to human sewage sources, recent precipitation, and water temperature were significant risk factors for bacterial detection in sentinel mussel batches. These findings are consistent with the hypothesis that filter-feeding invertebrates along the coast concentrate fecal bacteria flowing from land to sea and show that the relationships between anthropogenic effects on coastal ecosystems and the environmental niches of fecal bacteria are complex and dynamic. 相似文献
11.
Eiko Yabuuchi Toshio Miwatani Yoshifumi Takeda Michiko Arita 《Microbiology and immunology》1974,18(4):295-305
The flagellar morphology of 88 Vibrio parahaemolyticus strains, including a strain descended from Fujino's original strain EB101 (= ATCC17802 = KM1339) was studied. EB101 and 83 other strains (95%) showed mixed polar and peritrichous type of flagellation when grown on modified MOF (MMOF) agar after 16-hr incubation at 20 C. Cultures containing numerous peritrichous cells showed wiggly movements in moist preparations and rapidly spreading growth in semisolid agar plates. Peritrichous flagella were easily removed mechanically from the soma. The mean wavelengths of polar and peritrichous flagella were 2.53 μm (normal type) and 1.72 μm (atypical curly type) respectively. Peritrichous cells on solid media appeared after incubation for 2.5 hr at 37 C and 7 hr at 20 C. Overnight incubation at 37 C and acidity of the medium due to fermentation of carbohydrate markedly ruined peritrichous flagella. Electron micrograph of cells grown on MMOF agar revealed a sheathed polar flagellum and unsheathed peritrichous flagella. A hook structure was demonstrated at the proximal end of the latter. Polar monotrichous cultures in MMOF broth sometimes contained some cells having several or many peritrichous flagella of atypical curly type. Seven strains of Vibrio cholerae were exclusively polar monotrichous on solid and in liquid media. The flagellation of V. parahaemolyticus is concluded as being a mixed polar-peritrichous type. This fact would indicate that V. parahaemolyticus should be excluded from the genus Vibrio, since the genus Vibrio was defined as polar monotrichous. 相似文献
12.
Vibrio parahaemolyticus is a gram-negative, halophilic bacterium indigenous to marine and estuarine environments and it is capable of causing food and water-borne illness in humans. It can also cause disease in marine animals, including cultured species. Currently, culture-based techniques are used for quantification of V. parahaemolyticus in environmental samples; however, these can be misleading as they fail to detect V. parahaemolyticus in a viable but nonculturable (VBNC) state which leads to an underestimation of the population density. In this study, we used a novel fluorescence visualization technique, called recognition of individual gene fluorescence in situ hybridization (RING-FISH), which targets chromosomal DNA for enumeration. A polynucleotide probe labeled with Cyanine 3 (Cy3) was created corresponding to the ubiquitous V. parahaemolyticus gene that codes for thermolabile hemolysin (tlh). When coupled with the Kogure method to distinguish viable from dead cells, RING-FISH probes reliably enumerated total, viable V. parahaemolyticus. The probe was tested for sensitivity and specificity against a pure culture of tlh+, tdh−, trh−V. parahaemolyticus, pure cultures of Vibrio vulnificus, Vibrio harveyi, Vibrio alginolyticus and Vibrio fischeri, and a mixed environmental sample. This research will provide additional tools for a better understanding of the risk these environmental organisms pose to human health. 相似文献
13.
I. A. Beleneva E. F. Maslennikova T. Yu. Magarlamov 《Russian Journal of Marine Biology》2004,30(2):96-100
One hundred strains of halophilic vibrios were isolated from 16 species of marine invertebrates of Peter the Great Bay. Based on their morphological and biochemical characteristics, the bacteria were identified as Vibrio parahaemolyticus and Vibrio alginolyticus. Bacterial isolates possessed virulence enzymes (DNAase, lecithinase, catalase) and were characterized by a high enterotoxigenicity. It was determined that 76% of the V. parahaemolyticus strains and 43% of the V. alginolyticus strains were Kanagawa-positive. The isolates showed a high adhesive capability, the average adhesion index was 18.06 cells per erythrocyte for V. parahaemolyticus and 12.55 for V. alginolyticus. The results of this study suggest a high pathogenic potential of the isolated halophilic vibrios, which are an epidemic hazard to marine invertebrates and to humans. 相似文献
14.
Vibrio parahaemolyticus and Vibrio vulnificus in South America: water,seafood and human infections 总被引:3,自引:0,他引:3
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S.M. Raszl B.A. Froelich C.R.W. Vieira A.D. Blackwood R.T. Noble 《Journal of applied microbiology》2016,121(5):1201-1222
The bacterial species, Vibrio parahaemolyticus and Vibrio vulnificus, are ubiquitous in estuaries and coastal waters throughout the world, but they also happen to be important human pathogens. They are concentrated by filter‐feeding shellfish which are often consumed raw or undercooked, providing an important potential route of entry for an infective dose of these bacteria. Vibrio parahaemolyticus can cause abdominal cramping, nausea, diarrhoea, vomiting, chills and fever. Vibrio vulnificus can cause similar gastrointestinal‐related symptoms, but can also spread to the bloodstream, resulting in primary septicaemia, and it can also cause disease via wound infections. The objective of this article is to summarize, for the first time, the incidence and importance of V. parahaemolyticus and V. vulnificus in South America, in environmental waters and seafood, especifically molluscan shellfish, as well as human infection cases and outbreaks. It appears that infections from V. parahaemolyticus have been more strongly related to shellfish ingestion and have been more frequently reported on the Pacific coast of South America. Conversely, V. vulnificus has been more frequently acquired by water contact with open wounds and its presence has been more heavily reported along the Atlantic coast of South America, and while documented to cause serious mortality, have been relatively few in number. The impacts of El Nino Southern Oscillation (ENSO) have been observed to cause an increase in V. parahaemolyticus outbreaks on the Pacific coast of South America. The implementation of a regulated monitoring approach, along with the use of faster, more accurate and virulence‐specific detection approaches, such as PCR confirmation, should be considered to detect the presence of pathogenic Vibrio strains in environmental and seafood samples for protection of public health. Furthermore, improved clinical surveillance with suspected cases should be implemented. This review highlights the need for more research and monitoring of vibrios in South America, in water, shellfish and clinical samples. 相似文献
15.
Background
Vibrio parahaemolyticus is a marine seafood-borne pathogen causing gastrointestinal disorders in humans. Thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH) are known as major virulence determinants of V. parahaemolyticus. Most V. parahaemolyticus isolates from the environment do not produce TDH or TRH. Total V. parahaemolyticus has been used as an indicator for control of seafood contamination toward prevention of infection. Detection of total V. parahaemolyticus using conventional culture- and biochemical-based assays is time-consuming and laborious, requiring more than three days. Thus, we developed a novel and highly specific loop-mediated isothermal amplification (LAMP) assay for the sensitive and rapid detection of Vibrio parahaemolyticus. 相似文献16.
Background
Pandemic Vibrio parahaemolyticus has undergone rapid changes in both K- and O-antigens, making detection of outbreaks more difficult. In order to understand these rapid changes, the genetic regions encoding these antigens must be examined. In Vibrio cholerae and Vibrio vulnificus, both O-antigen and capsular polysaccharides are encoded in a single region on the large chromosome; a similar arrangement in pandemic V. parahaemolyticus would help explain the rapid serotype changes. However, previous reports on "capsule" genes are controversial. Therefore, we set out to clarify and characterize these regions in pandemic V. parahaemolyticus O3:K6 by gene deletion using a chitin based transformation strategy. 相似文献17.
Hirano T Aoki M Kadokura K Kumaki Y Hakamata W Oku T Nishio T 《Letters in applied microbiology》2011,53(2):161-166
Aims: To investigate the attractant effect of 4‐O‐(N‐acetyl‐β‐d ‐glucosaminyl)‐d ‐glucosamine (GlcNAc‐GlcN) in the chemotaxis of Vibrio bacteria that produce carbohydrate esterase (CE) family 4 chitin oligosaccharide deacetylase (COD), an enzyme that catalyzes the production of GlcNAc‐GlcN from N,N′‐diacetylchitobiose (GlcNAc)2. Methods and Results: The chemotactic effect of disaccharides from chitin on several strains of Vibrio bacteria was investigated using an agar gel lane‐migration method. The results demonstrated that GlcNAc‐GlcN functions as an effective chemoattractant in the CE family 4 COD‐producing vibrios, Vibrio parahaemolyticus and Vibrio alginolyticus. In contrast, this phenomenon was not observed in Vibrio nereis or Vibrio furnissii, which lack genes encoding this enzyme. From transmission electron microscope observation of V. parahaemolyticus cells following the chemotaxis assay, GlcNAc‐GlcN appears to stimulate polar flagellum rotation. Conclusions: GlcNAc‐GlcN is a specific chemoattractant for the CE family 4 COD‐producing vibrios, V. parahaemolyticus and V. alginolyticus. Significance and Impact of the Study: It was clarified for the first time that GlcNAc‐GlcN functions as a signalling molecule in the chemotaxis of Vibrio bacteria that have an ability to produce CE family 4 COD, which generate GlcNAc‐GlcN from (GlcNAc)2. 相似文献
18.
Ksenia Matlawska-Wasowska Rebecca Finn Ana Mustel Conor P O'Byrne Alan W Baird Eleanor T Coffey Aoife Boyd 《BMC microbiology》2010,10(1):329
Background
Vibrio parahaemolyticus is a food-borne pathogen causing inflammation of the gastrointestinal epithelium. Pathogenic strains of this bacterium possess two Type III Secretion Systems (TTSS) that deliver effector proteins into host cells. In order to better understand human host cell responses to V. parahaemolyticus, the modulation of Mitogen Activated Protein Kinase (MAPK) activation in epithelial cells by an O3:K6 clinical isolate, RIMD2210633, was investigated. The importance of MAPK activation for the ability of the bacterium to be cytotoxic and to induce secretion of Interleukin-8 (IL-8) was determined. 相似文献19.
Bacteria of the genus Vibrio are an important component of marine ecosystems worldwide. The genus harbors several human pathogens, for instance the species
Vibrio parahaemolyticus, a main cause for foodborne gastroenteritis in Asia and the USA. Pathogenic V. parahaemolyticus strains emerged also in Europe, but little is known about the abundance, pathogenicity and ecology of V. parahaemolyticus especially in Northern European waters. This study focuses on V. parahaemolyticus and its close relative Vibrio alginolyticus in the North Sea (Helgoland Roads, Germany). Free-living, plankton-attached and shellfish-associated Vibrio spp. were quantified between May 2008 and January 2010. CFUs up to 4.3 × 103 N l−1 and MPNs up to 240 N g−1 were determined. Phylogenetic classification based on rpoB gene sequencing revealed V. alginolyticus as the dominant Vibrio species at Helgoland Roads, followed by V. parahaemolyticus. We investigated the intraspecific diversity of V. parahaemolyticus and V. alginolyticus using ERIC-PCR. The fingerprinting disclosed three distinct groups at Helgoland Roads, representing V. parahaemolyticus, V. alginolyticus and one group in between. The species V. parahaemolyticus occurred mainly in summer months. None of the strains carried the virulence-associated genes tdh or trh. We further analyzed the influence of nutrients, secchi depth, temperature, salinity, chlorophyll a and phytoplankton on
the abundance of Vibrio spp. and the population structure of V. parahaemolyticus. Spearman Rank analysis revealed that particularly temperature correlated significantly with Vibrio spp. numbers. Based on multivariate statistical analyses we report that the V. parahaemolyticus population was structured by a complex combination of environmental parameters. To further investigate these influences is
the key to understanding the dynamics of Vibrio spp. in temperate European waters, where this microbial group and especially the pathogenic species, are likely to gain in
importance. 相似文献
20.
A study was conducted to investigate the involvement of bacteria in oyster mortalities during summer. Moribund and apparently
healthy oysters were sampled during mortality events along the French coast and in rearing facilities, usually when temperature
reached 19°C or higher, and oysters were in the gonadal maturation phase. Hemolymph samples were aseptically withdrawn and
submitted to bacteriological analysis. In healthy oysters, bacteria colonized hemolymph at low concentrations depending on
the location. In most moribund oysters, bacteria were present in hemolymph and other tissues. These bacterial populations
were more often diverse in oysters originating from the open sea than from facilities where animals were generally infected
by a single type of bacterium. Only the dominant colonies were identified by phenotypic and genotypic characters (RFLP of
GyrB gene and partial sequence of 16S rRNA gene). They belonged to a limited number of species including Vibrio aestuarianus, members of the V. splendidus group, V. natriegens, V. parahaemolyticus, and Pseudoalteromonas sp. The most frequently encountered species was V. aestuarianus (56% of isolates), which was composed of several strains closely related by their 16S rRNA gene but diverse by their phenotypic
characters. They appeared intimately linked to oysters. The species within the V. splendidus group were less prevalent (25% of isolates) and more taxonomically dispersed. A majority of the dominant strains of V. aestuarianus and V. splendidus group injected to oysters induced mortality, whereas others belonging to the same species, particularly those found in mixture,
appeared innocuous. 相似文献