Bacterial Fish Pathogens of L forms in fish diseases To date L forms have been

Bacterial fish pathogens of l forms in fish diseases

This preview shows page 149 - 151 out of 594 pages.

Bacterial Fish Pathogens of L-forms in fish diseases. To date, L-forms have been described for Aer. salmonicida and Y. ruckeri (Mcintosh and Austin, 1990a). Mycoplasma mobile Cultures produce 'Tried-egg" colonies of 10-500 |im diameter on Hayflick medium, which contains horse or bovine serum, after incubation at an unstated temperature for 2-6 days. Colonies contain filterable (through the pores of 0.45 |im pore size filters). Gram-negative, conical or flask-shaped, wall-less cells with distinctive terminal structures. The cells demonstrate marked ability to adhere to and glide on glass, plastic, erythrocytes and tissue culture cells. Growth occurs at 4-30°C, but not at 37°C. Catalase (weak), oxidase (weak) and phospha- tase (weak) are produced. Blood is degraded, but not arginine, casein, gelatin or urea. Acid is produced fermentatively from arabinose, fructose, galactose, glucose, lactose, maltose and mannose. 2,3,5-Triphenyltetrazolium chloride and potassium tellurite (weakly) are reduced, but not methylene blue. Gluconate is not oxidised, nor is phenylalanine deaminated. The G + C ratio of the DNA is 22.4-24.6 mol % (KiYchhof[ et aL, 1987). Serologically, the tench isolate was distinct from all other vaHdly described species of Acholeplasma and Mycoplasma. From the traits listed above it was deemed that the organism formed a new species, for which the name of Mycoplasma mobile was coined (Kirchhoff e^ aL, 1987). Myxococcaceae representative Myxococcus piscicola There has been one report of gill disease (in 1972) caused by a supposed new species of the fruiting organism Myxococcus, for which the name of Myxococcus piscicola was suggested (Xu, 1975). This organism was associated with an epizootic in grass carp (Ctenopharyngodon idelluls) fingerlings held in ponds in Wuhan, China. Conical fruiting bodies were produced on agar. These fruiting bodies were surrounded by a thin membrane, without peduncle or branches (Xu, 1975). Oxalobacteraceae representative Janthinobacterium lividum Pure cultures have been recovered and characterised: Janthinobacterium lividum Cultures comprise purple-pigmented, motile. Gram-negative, strictly aerobic rods, which produce arginine dihydrolase, catalase and oxidase, but not P-galactosidase,
Image of page 149
Characteristics of the pathogens: Gram-negative bacteria 127 indole or tryptophan deaminase. Nitrates are reduced, and the Voges Proskauer reaction is positive. Gelatin, but not urea, is degraded. Growth occurs at 4-30°C but not 37°C, and in 0-2%, but not 3% (w/v), sodium chloride. Caprate, citrate, malate, maltose, mannitol, mannose and phenylacetate are utilised, but not TV- acetyl-glucosamine or adipate. From these traits, the organisms were identified as typical (Table 4.3; from Northern Ireland) and atypical (Table 4.3; from Scotland) Janthinobacterium lividum (Sneath, 1984; Logan, 1989). Pasteurellaceae representative Pasteurella skyensis Four isolates were obtained from diseased Atlantic salmon (Birkbeck et ai, 2002).
Image of page 150
Image of page 151

You've reached the end of your free preview.

Want to read all 594 pages?

  • Spring '20
  • Bacteria, representative, gram-negative bacteria

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes
A+ icon
Ask Expert Tutors