The development of an assay to quantitate chondroitin AC lyase activity of Cytophaga columnaris isolates is described. Assay conditions were defined by using C. columnaris originally isolated from channel catfish Ictalurus punctatus , coho salmon Oncorhynchus kisutch , goldfish Carassius auratus , and striped bass Morone saxatilis affected with clinical columnaris disease. Supernatant and cellular components of broth cultures exhibited strong activity, and rates of chondroitin sulfate degradation ranged from 20.0 to 81.4 μg/(mL.h) for the cell component and from 35.4 to 83.4 μg/(mL.h) for the supernatant. Degradation rates were calculated by simple linear regression analysis, and most correlations ranged from −0.90 to −1.00. The assay provided results within 2–3 h, and the enzyme is active under a wide range of pH (5–9) and temperature (10–50°C) conditions. The assay can be used as a simple diagnostic aid to differentiate C. columnaris from Cytophaga psychrophila , but more importantly, as a quantitative tool to explore any relationship between specific chondroitin lyase activity and columnaris disease.

Journal of Aquatic Animal Health↗

USGS1993

Nonselective nature of coomassie brilliant blue agar for the presumptive identification of Aeromonas salmonicida in clinical specimens

No abstract available.

Diseases of Aquatic Organisms↗

USGS1993

Low survival rate of Atlantic salmon eggs believed due to Cytophaga psychrophila

No abstract available at this time

Research Information Bulletin↗

USGS1992

Detection of Aeromonas salmonicida the mucus of salmonid fishes

Mucus of salmonids was evaluated as a source for nonlethal detection of the pathogen Aeromonas salmonicida in fish. The bacterium was readily isolated from mucus on dilution plates when Coomassie Brilliant Blue agar was the primary plating medium. Kidney samples from the fish that served as sources of mucus were similarly processed. Infection was detected in 56% of mucus samples from lake trout Salvelinus namaycush that were undergoing an epizootic of furunculosis, but only 6% of the kidneys from these fish were positive for the pathogen. Only 1% of asymptomatic brown trout Salmo trutta sampled at another fish hatchery had A. salmonicida in their mucus, and none had a kidney infection. Combined results from the examination of two pools of Atlantic salmon Salmo salar reared at a third hatchery indicated that 37% of these fish had mucus infections caused by A. salmonicida , but only 4% of the kidneys were infected.

Journal of Aquatic Animal Health↗

USGS1991

Isolation and phenotypic characterization of an oxidase-negative Aeromonas salmonicida causing furunculosis in coho salmon (Oncorhynchus kisutch)

An oxidase-negative Aeromonas salmonicida was isolated from coho salmon ( Oncorhynchus kisutch ) suffering from an epizootic of furunculosis at the state hatchery near Belfair, Washington. Typical, oxidase-positive A. salmonicida was isolated concurrently from the same population of fish. Mortality was controlled with medicated feed treatments. Evidence supporting the identification of the two types of A. salmonicida is presented. Methods for the proper identification of oxidase-negative A. salmonicida isolates are evaluated.

Journal of Wildlife Diseases↗