from: Aeromonas (Edited by: Joerg Graf). Caister Academic Press, U.K. (2015) Pages: 3-44.
Since its description by Kluyver and van Niel in 1936, the taxonomic structure of the genus Aeromonas has been drastically reshaped each time new technological advances were made in bacterial systematics. Modern Aeromonas taxonomy started off at the end of the 1970s essentially relying on physiological and biochemical characterization and DNA-DNA hybridizations, the latter still being considered the ‘golden standard' for delineation of bacterial species. The original ‘four-species concept' encompassing Aeromonas hydrophila, Aeromonas caviae, Aeromonas sobria and Aeromonas salmonicida was soon expanded with multiple DNA hybridization groups (HGs), most of which were later given the species status. The introduction of 16S rRNA gene sequence analysis and amplified fragment length polymorphism (AFLP) fingerprinting in the 1990s allowed to characterize the phylogenetic and genotypic diversity of larger sets of Aeromonas isolates, and facilitated the description of several new Aeromonas species or the synonymization of existing taxa. Next, the availability of bacterial whole-genome sequences allowed to evaluate single-copy protein-encoding housekeeping genes such as gyrB and rpoD as alternative molecular markers in Aeromonas taxonomy. Compared to the 16S rRNA gene, these markers display a higher taxonomic resolution and can be combined in a multi-locus sequence approach to construct a stable phylogenetic framework to rapidly and reliably recognize new Aeromonas taxa and thus avoid new nomenclatural problems read more ...