Numerical Taxonomy of Bacterial Isolates Associated with a Freshwater Fishery

Phenetic data on over 600 aerobic, heterotrophic, aquatic bacteria from a freshwater fish farm were collected and examined by numerical taxonomy procedures using 124 unit characters. Reference cultures representing 36 taxa were included in the analyses. The data were examined using the simple matching (SSM) and Jaccard (S J) coefficients, and clustering was achieved using unweighted average linkage. At similarity values of 70% or above as defined with the S J coefficient, 82% of the environmental isolates were recovered in 14 major and 56 minor phena. The major phena were equated with Acinetobacter calcoaceticus, Aeromonas hydrophila, Aeromonas salmonicida, Alcaligenes sp., coryneforms, Enterobacter aerogenes, Escherichia coli, Hafnia alvei, Pseudomonas fluorescens, Pseudomonas spp. (two groups), Serratia sp., Vibrio fluvialis and Yersinia sp. The minor phena comprised Agrobacterium, Arthrobacter, Bacillus, Bordetella, Cytophaga, Erwinia, Flavobacterium, Flexibacter, Klebsiella, Micrococcus, Moraxella, Staphylococcus and Vibrio. Aeromonas salmonicida was recovered only from moribund and dead rainbow trout (Salmo gairdneri) during an outbreak of furunculosis. In contrast, coryneforms (phenon 2) and Alcaligenes (phenon 14) were found exclusively in water samples.