Nine isolates of bacteria recovered from fish dying at
marine facilities were collected from different geographic areas.
The strains included: an isolate from chinook salmon (Oncorhynchus
tshawytscha) reared in net pens in New Zealand, an isolate
from chum salmon (Oncorhynchus keta) held at a laboratory in
Oregon, USA., and seven strains recovered from tilapia (Oreochromis spilurus),
silvery black porgy (Acanthopagrus cuvieri), and
greasy grouper (Epinenhelus tauvina) cultured in Kuwait. All
isolates were characterized by examination of morphological and
biochemical properties and were confirmed to be members of the
genus Vibrio.
All isolates differed phenotypically from each other, from
vibrios known to be pathogenic for fish, and from other named
Vibrio species. Analysis of key phenotypic characteristics used
to establish existing species suggested that the isolates tested
were new Vibrio species.
Four of the isolates (two from coldwater fish and two from
warmwater fish) were selected for further study. This included
determination of percent guanine plus cytosine (%G+C), comparison
of growth characteristics, analysis of major 0 antigens and
testing of pathogenicity.
The four isolates examined had an absolute requirement for
NaCl. Optimum growth temperatures varied among the isolates and
were consistent with the temperature optima of the hosts from
which the isolates were obtained.
Serological analysis using slide agglutination, microtiter
agglutination, and Ouchterlony double diffusion tests detected
specific thermostable (0) antigens unique for each of the four
isolates. A common minor antigen was observed between two of the
other isolates from Kuwait.
Experimental infections were produced in fingerling rainbow
trout (Salmo gairdneri) using intraperitoneal injection of the
four isolates. The pathogenicity of the two isolates from Kuwait
was higher than that of the two salmonid isolates. The strains
from Kuwait were used to challenge juvenile chinook salmon by
waterborne exposure. The pathology produced by infection was
characteristic Gram-negative hemorrhagic septicemia. / Graduation date: 1988
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28831 |
| Date | 15 September 1987 |
| Creators | Pipoppinyo, Somsak |
| Contributors | Winton, James R. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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