Gram negative rods of 2 30 X 05 im in size which occasionally form filaments of

Gram negative rods of 2 30 x 05 im in size which

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yellow, flat, thin colonies, containing strictly aerobic. Gram-negative rods of 2- 30 X 0.5 |im in size, which occasionally form filaments of up to 100 |im in length. In older cultures, cells become spherical (~0.5 jim in diameter). Microcysts do not occur. Gliding movement is a characteristic feature of all isolates. Catalase and oxidase are produced, but not H2S or indole. Nitrates are not reduced. The methyl red test is negative. Casein, gelatin, tributyrin and tyrosine are degraded, but not aesculin, agar, cellulose, chitin, starch or urea. Growth occurs from 14.6-34.3°C, and at pH 6-9. There are requirements for potassium chloride and sodium chlor- ide. Acid is not produced from arabinose, cellobiose, glucose, lactose, mannitol, raffinose, salicin, sucrose or xylose. Isolates are capable of lysing dead cells of Aer. hydrophila, Edw. tarda, Esch. coli and V. anguillarum, but not Bacillus sub tills. The G + C ratio of the DNA is 31.3-32.5 mol % (Hikida et al, 1979; Wakabayashi et ai, 1986). All isolates share a common antigen (Wakabayashi et ai, 1984). From these traits, Hikida et al. (1979) proposed that the organism belonged in an as yet undescribed species of Flexibacter, for which the name of Fie. marinus was mooted. Subsequently, Wakabayashi et al. (1986) formally proposed the name of Fie. maritimus to accommodate the pathogen. Independently, Reichenbach (1989) proposed the name of Cyt. marina for the same organism. However, the organism was subsequently reclassified in a newly described genus Tenacibaculum, as T. mar- itimum (Suzuki et al., 2001). The intraspecific diversity of 29 fresh isolates and 3 reference cultures has been addressed using RAPDs with the outcome that two principle (and distinct serological) groups were recognised, of which one contained all the cultures from sole and gilthead sea bream, and the second group comprised isolates from Atlantic salmon, turbot and yellowtail. Interestingly, the reference strains were not recovered with the fresh isolates, and may reflect the problem of using archived cultures which have been long removed from their natural habitat (Avendano-Herrera et al., 2004b). A further publication by this group (Avendano- Herrera et al, 2004c, 2005a) defined three serotypes, i.e. Ol, 02 and 03, which were regarded as host-specific, with serotype Ol, 02 and 03 comprising isolates from sole and gilthead sea bream, turbot and sole, respectively. Tenacibaculum ovolyticum (= Flexibacter ovolyticus) The 35 isolates were described as comprising: Tenacibaculum 0volyticum Pale yellow-pigmented, long, slender (0.4 x 2-20 |im). Gram-negative rods, which demonstrate gHding movement. Catalase and oxidase are produced, but not so
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122 Bacterial Fish Pathogens arginine dihydrolase, P-galactosidase, H2S, indole or lysine or ornithine de- carboxylase. Nitrates are reduced. DNA, gelatin, Tween 80 and tyrosine, but not agar, cellulose, chitin, starch or urea, are degraded. Acid is not produced aero- bically from arabinose, cellobiose, glucose, lactose, mannitol, raffinose, salicin, sucrose or xylose. Growth occurs at 4-30°C, but not 35°C, and in >3% (w/v) sodium chloride. The G + C ratio of the DNA was reported as 31.0 mol % (Hansen et ciL, 1992).
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