Development of a DNA probe using differential hybridization to detect the fish pathogenVibrio anguillarum.

The fish pathogenVibrio anguillarum causes significant economic losses in commercially cultured fish species worldwide. At present, identification ofV. anguillarum requires conventional isolation and culturing techniques. Using differential hybridization, a 310 base pairV. anguillarum-specific DNA fragment was isolated for use as a probe. In specificity studies against 19 different bacterial species, including twoVibrio sp. and fish pathogens, and 223 marine bacterial isolates, the probe hybridized exclusively toV. anguillarum strains. The probe also strongly hybridizes to 7 of 9 serotypes tested, with serotype 09 giving a weak probe reaction and serotype O7 negative. The probe allows rapid and accurate detection of both pathogenic and environmental strains ofV. anguillarum.

The detection of fish pathogenVibrio anguillarum in water and fish using a species-specific DNA probe combined with membrane filtration.

The marine bacteriumVibrio anguillarum causes disease in fish worldwide and is particularly devastating in aquaculture. Little is known about the ecology ofV. anguillarum in the environment and how this may relate to the pathogenicity of this organism. Combining membrane filtration and a species-specific DNA probe, culturableV. anguillarum cells were detected in water from three habitats and in chinook salmon (Onchorynchus tshawytscha) tissue samples. Results show that different marine habitats have a marked effect on cell numbers and that water temperature may play a role in the culturability and distribution ofV. anguillarum. Vibrio anguillarum was detected from the gills of salmon within 24 h of transfer of fingerlings from freshwater to seawater, with cell numbers reaching a concentration of 1.9 × 10(2) cells g(-1) tissue 28 days post transfer.Vibrio anguillarum cell numbers were low in the colon throughout the study, andV. anguillarum was not detected in healthy kidney samples. The methodology reported in this paper allows the accurate quantification of culturableV. anguillarum cells and has allowed a preliminary study of the ecology of this species.

An aspect of microbiology research in New Zealand: the pursuit of water quality.

CONCLUSION: The problems in monitoring and assessing water quality that must be overcome most urgently are associated with the development of appropriate, simple methods for detecting living but not necessarily growing indicator and pathogenic microorganisms. These methods will allow us to assess and monitor water quality, understand the survival and distribution of microbial contaminants and truly assess the health implications of their presence in water.

A method for detecting human enteroviruses in aquatic sediments.

A method is described for detecting enteroviruses in both freshwater and marine sediments. Viruses were recovered from sediments by elution into 6% beef extract at pH 9.0 and concentration with polyethylene glycol 6000. The recovery efficiency ranged from 6 to 55% for marine sediments and 16 to 77% for freshwater sediments. Although the efficiency of the method was influenced by the composition and source of the sediments it was used successfully to detect viruses occurring in marine and freshwater sediments near sewer outfalls.

Contribution of periphytic bacteria to the concentration of chromium in the crabHelice crassa.

Periphytic bacteria found on the carapace and gills of crabs collected from near a tannery effluent outlet were shown to be able to concentrate chromium. By concentrating Cr, the bacteria contributed to the total Cr concentration of the crabs. Since crabs and other crustaceans are eaten by bottom feeding fish, bacteria may be contributing to the passage of Cr up the food chain.