Characteristics of the pathogens Gram negative bacteria 143 are utilised

Characteristics of the pathogens gram negative

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Characteristics of the pathogens: Gram-negative bacteria 143 are utilised. Sensitivity is recorded to the vibriostatic agent, 0/129. The G + C ratio of the DNA is 43-45 mol %. V. logei Fifteen Icelandic and one Norwegian isolates from shallow skin lesions in Atlantic salmon were considered to be similar to V. logei (Benediktsdottir et al, 1998). Vibrio logei Cultures do not produce arginine dihydrolase, indole or lysine or ornithine de- carboxylase. Blood (haemolysis) and chitin are degraded, but not starch. Acid is produced from vV-acetyl glucosamine, glycerol, maltose, mannose, ribose, sucrose and trehalose. F. ordalii The establishment of a new species to accommodate strains previously classified as V. anguillarum biotype II, i.e. V. ordalii (Schiewe, 1981; Schiewe et ai, 1981), generated an awareness that vibriosis could be caused by more than one bacterial taxon. Disease caused by V. ordalii has been documented in Japan (e.g. Muroga et ai, 1986) and the Pacific Northwest, U.S.A. V. ordalii was homogeneous by plasmid profiling, ribotyping and serogrouping, accommodated two LPS groups, and was heterogeneous by BIOLOG-GN fingerprints and API 20E profiles (Austin et ai, 1997). Vibrio ordalii Cultures comprise fermentative. Gram-negative, curved rods of 2.5-3.0 x 1.0 |im in size, motile by means of single polar flagella. Growth occurs quite slowly, insofar as 4-6 days incubation at 22°C are required for the production of off- white, circular, convex colonies of 1-2 mm in diameter on seawater agar. V. ordalii is, however, not especially active. Catalase and oxidase are produced, but not arginine dihydrolase, P-galactosidase, H2S, indole, lysine or ornithine decarboxyl- ase, or phenylalanine deaminase. DNA, chitin (by some isolates) and gelatin are degraded, but not aesculin, lipids, pectate, starch or urea. Nitrates are reduced by some isolates. The methyl red test and Voges Proskauer reaction are negative. Tartrate is utilised. Only a few carbohydrates, e.g. galactose (variable result), maltose, mannitol and sucrose are attacked with the production of acid. Negative responses are recorded for adonitol, arabinose, cellobiose, dulcitol, erythritol, glycerol, inositol, lactose, melibiose, raffinose, rhamnose, saHcin, sorbitol, treha- lose and xylose. Growth occurs at 15-22°C, but not at 37°C, and in 0.5-3.0%, but not 0% or 7% (w/v), sodium chloride. Sensitivity is recorded to the vibriostatic agent, 0/129. The G + C ratio of the DNA is 43-44 mol % (Schiewe, 1981; Schiewe et ai, 1981; Austin et ai, 1997).
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144 Bacterial Fish Pathogens Results of DNA: DNA hybridisation studies have confirmed the homogeneity and vaHdity of V. ordain, with intraspecific homologies of approximately 80%. There is only a 58-59% association with V. anguillarum (Schiewe et al., 1981). V. ordalii contains plasmids (Tiainen et al., 1995), but the profile is inevitably different from V. anguillarum. In one study, Schiewe and Crosa (1981) determined that 11 isolates of V. ordalii contained a common plasmid type (pMJlOl) with a molecular weight of 20mDa. Indeed, this plasmid (=~32kb) is common to all V. ordalii isolates (Pedersen et ai, 1996b).
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