A study of unusual metabolic variants of <italic>Aeromonas caviae</italic> and <italic>Aeromonas hydrophila</italic> using a polyphasic taxonomic approach

Abstract

Variation in acid production from carbohydrate metabolism has been identified in <italic>Aeromonas</italic> as a potential indicator for new subspecies. Therefore, pure cultures of non-lactose fermenting <italic>Aeromonas caviae</italic>, a cause of waterborne infections in humans and other vertebrates, were studied after noting a mixture of acid producing and non-acid producing colonies after four days of incubation on MacConkey agar at ambient temperature. Unusual arabinose negative strains of <italic>A. hydrophila</italic> (usually arabinose positive) were added to the project to further study the correlation between carbohydrate fermentation and taxonomy. These metabolic variants of <italic>A. caviae</italic> and <italic>A. hydrophila</italic> were studied for phenotypic differences via carbohydrate utilization assays as well as genotypic differences via FAFLP. The results suggest that the <italic>A. caviae</italic> isolates MB3 and MB7 should be considered novel subspecies, while the arabinose negative strain designated <italic>A. hydrophila</italic> subsp. <italic>dhakensis</italic> is correctly identified as a subspecies of <italic>A. hydrophila</italic>.