Role of Bacteria in Bioaccumulation of Mercury in the Oyster Crassostrea virginica

Tissue-specific metabolism was monitored in gill, mantle, and adductor muscle of the oyster Crassostrea virginica over a time course of 96 h of anoxia followed by 48 h of recovery from anoxia. Succinate and alanine accumulated as products of anaerobic metabolism while aspartic acid was utilized as a substrate of anaerobiosis. The imino acids alanopine and strombine were not produced during anoxia. During aerobic recovery tissue levels of metabolites returned to control levels, succinate within 2 h in mantle and gill and 6 h in muscle, while restoration of alanine levels required about 24 h. Aspartate pools were restored in 4 to 6 h. Alanopine and strombine accumulated during the recovery period. By 2 h of recovery, alanopine content of mantle and gill had risen by 1.3 and 0.5 μmol/g, respectively, while in adductor muscle both alanopine and strombine accumulated with net increases of 2 and 2.7 μmol/g. Imino acid content declined after 6–12 h of recovery returning to control levels by 24 h. The roles of alanopine and strombine in the oyster are not as products of anaerobic metabolism but rather as products of glycolytic function during recovery. The increased metabolic rate associated with the return to aquatic conditions appears to require some glycolytic energy production to meet overall tissue energy requirements of recovery.

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Role of Type IV Pilins in Persistence of Vibrio vulnificus in Crassostrea virginica Oysters

Applied and Environmental Microbiology ◽

10.1128/aem.00641-07 ◽

2007 ◽

Vol 73 (15) ◽

pp. 5041-5044 ◽

Cited By ~ 37

Author(s):

Rohinee N. Paranjpye ◽

Asta B. Johnson ◽

Anne E. Baxter ◽

Mark S. Strom

Keyword(s):

United States ◽

Epithelial Cells ◽

Crassostrea Virginica ◽

Biofilm Formation ◽

Vibrio Vulnificus ◽

The United States ◽

Type Iv ◽

Abiotic Surfaces ◽

Prepilin Peptidase

ABSTRACT Vibrio vulnificus is part of the natural estuarine microflora and accumulates in shellfish through filter feeding. It is responsible for the majority of seafood-associated fatalities in the United States mainly through consumption of raw oysters. Previously we have shown that a V. vulnificus mutant unable to express PilD, the type IV prepilin peptidase, does not express pili on the surface of the bacterium and is defective in adherence to human epithelial cells (R. N. Paranjpye, J. C. Lara, J. C. Pepe, C. M. Pepe, and M. S. Strom, Infect. Immun. 66:5659-5668, 1998). A mutant unable to express one of the type IV pilins, PilA, is also defective in adherence to epithelial cells as well as biofilm formation on abiotic surfaces (R. N. Paranjpye and M. S. Strom, Infect. Immun. 73:1411-1422, 2005). In this study we report that the loss of PilD or PilA significantly reduces the ability of V. vulnificus to persist in Crassostrea virginica over a 66-h interval, strongly suggesting that pili expressed by this bacterium play a role in colonization or persistence in oysters.

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Additional Evidence that Juvenile Oyster Disease Is Caused by a Member of the Roseobacter Group and Colonization of Nonaffected Animals by Stappia stellulata-Like Strains

Applied and Environmental Microbiology ◽

10.1128/aem.66.9.3924-3930.2000 ◽

2000 ◽

Vol 66 (9) ◽

pp. 3924-3930 ◽

Cited By ~ 56

Author(s):

Katherine J. Boettcher ◽

Bruce J. Barber ◽

John T. Singer

Keyword(s):

Crassostrea Virginica ◽

Novel Species ◽

Host Factors ◽

Invertebrate Host ◽

Roseobacter Group ◽

Disk Diffusion Assay ◽

Diffusion Assay ◽

Juvenile Oyster Disease

ABSTRACT Juvenile oyster disease (JOD) causes significant annual mortalities of hatchery-produced Eastern oysters, Crassostrea virginica, cultured in the Northeast. We have reported that a novel species of the α-proteobacteria Roseobacter group (designated CVSP) was numerically dominant in JOD-affected animals sampled during the 1997 epizootic on the Damariscotta River, Maine. In this study we report the isolation of CVSP bacteria from JOD-affected oysters during three separate epizootics in 1998. These bacteria were not detected in nonaffected oysters at the enzootic site, nor in animals raised at a JOD-free site. Animals raised at the JOD enzootic site that were unaffected by JOD were stably and persistently colonized by Stappia stellulata-like strains. These isolates (designated M1) inhibited the growth of CVSP bacteria in a disk-diffusion assay and thus may have prevented colonization of these animals by CVSP bacteria in situ. Laboratory-maintained C. virginica injected with CVSP bacteria experienced statistically significant elevated mortalities compared to controls, and CVSP bacteria were recovered from these animals during the mortality events. Together, these results provide additional evidence that CVSP bacteria are the etiological agent of JOD. Further, there are no other descriptions of specific marine α-proteobacteria that have been successfully cultivated from a defined animal host. Thus, this system presents an opportunity to investigate both bacterial and host factors involved in the establishment of such associations and the role of the invertebrate host in the ecology of these marine α-proteobacteria.

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Use of Diacetyl To Reduce the Load of Vibrio vulnificus in the Eastern Oyster, Crassostrea virginica

Journal of Food Protection ◽

10.4315/0362-028x-66.1.38 ◽

2003 ◽

Vol 66 (1) ◽

pp. 38-43 ◽

Cited By ~ 17

Author(s):

J. M. BIRKENHAUER ◽

J. D. OLIVER

Keyword(s):

Crassostrea Virginica ◽

Vibrio Vulnificus ◽

Natural Populations ◽

Eastern Oyster ◽

Human Pathogen ◽

Highly Virulent

Vibrio vulnificus is a highly virulent human pathogen that occurs naturally among the microflora of oysters. This organism has two portals of entry into humans, one of which is ingestion. Oysters containing V. vulnificus consumed in a raw or undercooked state often serve as a vehicle for the transmission of this organism. Previous studies conducted in our laboratory have examined various generally recognized as safe compounds and have determined that diacetyl, a component of butter, is among the most effective of these compounds in reducing loads of V. vulnificus in oysters. The purpose of this study was to further examine the role of diacetyl, along with that of depuration, in reducing loads of V. vulnificus. Shellstock oysters were treated with various concentrations of diacetyl, and we found that many of the oysters ceased pumping when diacetyl was added. The data obtained in this study indicated that treatment with diacetyl is ineffective; however, any reduction in V. vulnificus numbers may be masked when groups of oysters, some of which may not have taken up diacetyl, are sampled. We then investigated the efficacy of diacetyl in lowering levels of V. vulnificus in shucked oysters. Diacetyl was found to significantly reduce the load of V. vulnificus in shucked oysters containing natural populations. Overall, it appears that treatment with diacetyl is ineffective for shellstock oysters, although it has potential for use in reducing loads of V. vulnificus in shucked oysters.

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