With the exception of acid production from arabinose raffinose and sucrose

With the exception of acid production from arabinose

This preview shows page 131 - 133 out of 594 pages.

With the exception of acid production from arabinose, raffinose and sucrose, there is good agreement with the description of Sal. enterica subsp. arizonae (Popoff and Le Minor, 2005). Serratia liquefaciens During Spring and early Summer of 1988, heavy mortalities, i.e. up to 30% of the stock, were noted among three separate populations of Atlantic salmon (Salmo salar L.), two of which (average weight = 450 g) were in Scottish marine cage sites, and the third population (average weight = 25 g) was in freshwater. Microscopic examination of formalin-fixed kidney sections indicated the presence of Gram-negative bacteria which exhibited bipolar staining. These organisms were recovered as dense, pure culture growth from diseased tissues, and were examined bacteriologically (Mcintosh and Austin, 1990b). Since the initial occurrence, the disease has been recognised on another two marine sites in Scotland during 1990. Also in 1990, the organism was recognised as the cause of low, continuous mortahties among farmed turbot in France (Vigneulle and Baudin-Lauren9in, 1995). Serratia liquefaciens Cultures comprise Gram-negative, fermentative, catalase-positive rods of 2-3 |im in length which, in contrast to the normal characteristics of the Enterobacteriaceae (Grimont and Grimont, 2005a), are motile by single polar flagella. Intracellular, bipolar staining properties are exhibited. Catalase, P-galactosidase and lysine and ornithine decarboxylase are produced, but not H2S, indole or tryptophan deaminase. The results of the oxidase test are variable, i.e. from negative to weakly positive, depending to some extent on the age of the culture. The methyl red test and Voges Proskauer reaction is negative. Nitrates are not reduced. Blood (P- haemolysis), casein, DNA, lecithin (weak), tributyrin (slow), Tween 20, 40, 60 and 80, and tyrosine are degraded, but not chitin, elastin, starch or urea. Growth
Image of page 131
Characteristics of the pathogens: Gram-negative bacteria 109 occurs at 4-37°C, in 0-5% (w/v), but not 7% (w/v) sodium chloride, and on deoxycholate citrate agar, eosin methylene blue agar and MacConkey agar, but not in 40% (v/v) bile salts. Sodium citrate, but not sodium malonate, is utilised. Acid is produced from amygdalin, arabinose, inositol, mannose, melibiose and saccharose, but not rhamnose. Acid and gas are produced from fructose, galac- tose, glucose, maltose, mannitol, melibiose, raffinose, sorbitol, sucrose, trehalose and xylose. The G + C ratio of the DNA is 55 mol % (Mcintosh and Austin, 1990b). Initially, it was considered that the organisms bore similarities to Aer. veronii (Hickman-Brenner et ai, 1987) and Ser. liquefaciens (Grimont and Grimont, 2005a). Similarities with the former included the presence of Gram-negative, fermentative, catalase- (and oxidase-) positive rods, which were motile by single polar flagella, and with a G + C ratio of the DNA of 55 mol %. Indeed, the only discrepancies with the definition o^ Aer. veronii concerned some sugar fermentation reactions. Yet, similar- ities were also apparent with Ser. liquefaciens. However, the use of the API 20E rapid identification system (profile = 5305363 or 5305367) and whole-cell agglutination,
Image of page 132
Image of page 133

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