HIGH-RESOLUTION GENOTYPIC ANALYSIS OF THE GENUS AEROMONAS BY AFLP FINGERPRINTING

We investigated the ability of a recently developed genomic fingerprin ting technique, named AFLP, to differentiate the 14 currently defined DNA hybridization groups (HGs) in the genus Aeromonas, We also determi ned the taxonomic positions of the phenospecies Aeromonas allosaccharo phila, Aeromonas encheleia, Aeromonas enteropelogenes, and Aeromonas i chthiosmia, which have not been assigned to HGs yet, A total of 98 Aer omonas type and reference strains were included in this study, For the AFLP analysis, the total genomic DNA of each strain was digested with restriction endonucleases ApaI and TaqI, Subsequently, restriction fr agments were selectively amplified under high-stringency PCR condition s, The amplification products were electrophoretically separated on a polyacrylamide gel and visualized by autoradiography. Following high-r esolution densitometric scanning of the resulting band patterns, AFLP data were further processed for a computer-assisted comparison, A nume rical analysis of the digitized fingerprints revealed 13 AFLP clusters which, in general, clearly supported the current Aeromonas taxonomy d erived from DNA homology data, In addition, our results indicated that there is significant genotypic heterogeneity in Aeromonas eucrenophil a (HG6), which may lead to a further subdivision of this species, A, a llosaccharophila and A. encheleia did not represent a separate AFLP cl uster but were found to be genotypically related to HG8/10 and HG6, re spectively, In addition, the results of the AFLP analysis also confirm ed the phylogenetic findings that A. enteropelogenes and A, ichthiosmi a are in fact identical to Aeromonas trota (HG13) and Aeromonas veroni i (HG8/10), respectively, The results of this study clearly show that the AFLP technique is a valuable new high-resolution genotypic tool fo r classification of Aeromonas species and also emphasize that this pow erful DNA fingerprinting method is important for bacterial taxonomy in general.