Aeromonas Salmonicida In Californian Trout (Oncorhynchus Mykiss, Walbaum, 1792 ) And Some Biochemical Characteristics Of This Bacteria
M Markovic, V Djikanovic, P Cakic, S Milosevic, Z Kulisic
aeromonas salmonicidae, biochemical activities, furunculosis, oncorhynchus mykiss
M Markovic, V Djikanovic, P Cakic, S Milosevic, Z Kulisic. Aeromonas Salmonicida In Californian Trout (Oncorhynchus Mykiss, Walbaum, 1792 ) And Some Biochemical Characteristics Of This Bacteria. The Internet Journal of Microbiology. 2006 Volume 3 Number 1.
The aim was to determine if the bacteria
Ten strains of the species
The taxonomy of genus
Three major routes of infection have been suggested for
In addition to trout,
Ewing et al. (1961), and Liu (1961) present data on the antigenic characteristics of
Cirkovic et al. (1998) working on problems of fish pathology on fisheries in Serbia show diversity of epizootiology situations according to sickness dispersion of different causes (viruses, bacteria, parasites and fungi). In their paper is presented fish diseases that, according to Federal Low for Animal Protection from diseases, endangers the whole country, and are very dangers for fish production and are obligate for registration and suppression. On the list of diseases is, between the others, and furunculosis.
Jeremic (1989), in her Ph.D. thesis, experimentalized with different vaccination methods against furunculosis in salmonids. The vaccine was prepared from field isolate from
In Serbia, activities in scientific area of fish bacteria are poorly, especially
Material And Methods
The material for this study originating from four salmonid fisheries in Serbia, during two years. A total of 140 fish specimens of californian trout (
Bacteriological examinations were performed on live and dead fishes with visible skin changes in the form of erosions or deeper necrotic lesions, which correspond to the expected alterations in trout furunculosis concerning appearance and shape.
The bacteria were isolated by sowing material from the mentioned skin areas and from organs (liver, spleen and kidneys) on two nutritive bacteriological media; bacto-tryptose agar and bacto-tryptose 5% blood agar. The treated media were incubated in a thermostat at 22-23°C and at 37°C. The samples were incubated for three days, and the growth on the medium surface was checked daily.
The characteristically formed colonies, round in shape with hemolysis and pigment, which multiplied at the temperature of 22-23°C, were isolated and resown on new media in order to obtain “clean” cultures for differentiation and typification. Typification was carried out on spaces bases, which were used for determining the biochemical activity of the isolated strains. Ali the isolated strains were examined by rapid serum agglutination on a plate, using diagnostic sera for rapid agglutination, namely an antiserum against
The pathogenicity of the isolated strains was checked on pig kidney tissue culture, by introducing sterile filtrates and observing the appearance of cytopathogenic effects in culture.
Results And Discussion
Ten strains of
The specific characteristics of the isolated strains of
The isolated strains were found to have the following characteristics: no H2S production in media; nitrates were positive; indol was negative; catalase was positive; V.P. was negative; esculin was positive. There was a zone of hemolysis around the grown colonies. Gelatin, glucose, arabinose and manitol were degraded but not saccharose. All isolated bacteria strains were immobile. The examined strains multiplied at a temperature of 22-23°C, while there was no growth at 37°C. The colonies of the examined strains produced a brown pigment after 3 to 5 days.
The results of agglutination reactions with anti “O” antisera to
The isolated strains of
All the isolated strains produced a toxin in the filtrate of the nutrient culture of the multiplied bacteria and its presence was confirmed by the appearance of a cytopathogenic effect on pig kidney tissue culture. Cytotoxins and enter toxins (including those with hemolytic activity) are the most important for their pathogenicity (Merino et al., 1992, 1995).
The results obtained in this work clearly demonstrate that the cause of furunculosis in trout is present in fisheries of Serbia and that
The biochemical activities of the isolated bacteria strains in our fisheries indicate that the isolated agent is very similar to that described by Griffin et al. (1953); Ewing et al. (1961); Popoff (1969) and Donlon et al. (1983).
The reactions of positive agglutination with the antiserum to the “O” antigen of the standard strain of
The results from this study indicate to validity of begining the research of
Ministry of Science and Environmental Protection, Project No. 143023 support this work.
Vesna Djikanovic “Sinisa Stankovic” Institute for Biological Research, Belgrade, Serbia Phone: +381 11 2078-357; Fax: +381 11 2761-433 E-mail: email@example.com