By DNADNA hybridisation and 16S 3RNA sequencing the closest neighbour was V

By dnadna hybridisation and 16s 3rna sequencing the

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By DNA:DNA hybridisation and 16S 3RNA sequencing, the closest neighbour was V. logei with 57% re-association (Lunder et al, 2000) and 98.8% sequence homology (Benediktsdottir et al, 2000), respectively. MISCELLANEOUS PATHOGENS Streptobacillus A possibly unique organism has been recovered from seawater-farmed Atlantic salmon in Ireland. The organism, which occurred intracellularly in tissues, was considered to be related to Streptobacillus moniliformis and fusobacteria on the basis of 16S rRNA analyses (Maher et al. (1995). UNNAMED BACTERIA There is an increasing awareness of diseases caused by apparently unique bacteria. For example, Sorimachi et al. (1993) and lida and Sorimachi (1994) described jaundice in yellowtail, attributed to an unknown filamentous bacterium of 4-6 |im
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Characteristics of the pathogens: Gram-negative bacteria 149 in length, which grew only in LI5 medium and Eagles MEM medium each supple- mented with 10% (v/v) foetal calf serum at 23-26°C. The unknown Gram-negative cocco-bacilH of Palmer et al. (1994) were char- acterised as follows: Unknown Grana-negative organism of Palmer et al. (1994) Cultures produce small colonies of 0.3 mm in diameter after incubation aerobically for 10-14 days. Anaerobic incubation results in larger colonies of 0.6 mm in diameter. Improved growth results by the addition of 0.5mg of L-cysteine hydro- chloride/1. Colonies are off-white, convex and granular, and contain non-motile. Gram-negative, P-haemolytic cocco-bacilli. Alkaline phosphatase (weakly pos- itive/variable), arginine dihydrolase, H2S (weakly positive/variable), indole (weakly positive/variable) and lipases are produced, but not oc-glucosidase, TV- acetyl glucosamine, catalase, P-galactosidase, P-glucuronidase, lysine decarboxyl- ase or oxidase. Nitrates are not reduced. The Voges Proskauer reaction is negative. Neither aesculin, gelatin, Tween 80 nor urea is attacked. Citrate is not utilised. Fructose, glucose and maltose are fermented, but not glycogen, lactose, mannitol, mannose, ribose, sucrose or xylose. Growth occurs at 10°C, but not at 37°C, and in 1-4%, but not 5% (w/v), sodium chloride. The organism was linked tenuously to the Neisseriaceae and Pasteurellaceae. The unnamed organism associated with Varracalbmi was described as follows: Causal agent of Varracalbmi The small, i.e. 1 mm in diameter, colonies, which grow anaerobically into the agar medium, comprise Gram-negative non-motile slender fermentative rods some- times arranged as short chains (when grown in broth), which produce arginine dihydrolase, oxidase but not catalase, indole or lysine or ornithine decarboxylase, attack starch (weakly) and lecithin (weakly) but not aesculin, casein, chitin, gelatin, Tween 20 or 80 or urea, and are non-haemolytic (ot-haemolysis was recorded after a week), require NaCl, and grow at 4-22°C, do not reduce nitrates, but are sensitive to the vibriostatic agent, 0/129. Growth occurs with galactose, glucose, glycerol, lactose, maltose, mannitol, mannose and sorbitol, but not arabinose, cellobiose, erythritol, melibiose, raffinose or rhamnose (Valheim et ai, 2000).
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  • Spring '20
  • Bacteria, representative, gram-negative bacteria

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