Genotypic diversity among Aeromonas isolates recovered from drinking water production plants as revealed by AFLP(TM) analysis

A novel DNA fingerprinting method, named AFLP(TM), was used to determine the genotypic diversity among 168 Aeromonas isolates originating from five drinking water production plants in Flanders, Belgium, The AFLP(TM) technique determines the genomic similarity between bacterial strains through numerical analysis of banding patterns generated by the electrophoretic separation of selectively amplified restriction fragments. Using an identification library (AER094) comprising AFLP fingerprints of 107 well-characterized Aeromonas strains, a total of 144 isolates (86%) could be allocated to one of the 14 DNA hybridization groups (HGs) so far recognized in the genus Aeromonas. The majority of these strains belonged to Aeromonas hydrophila HGs 2 and 3, Aeromonas caviae HGs 5A and 5B, Aeromonas sobria HG 7, and Aeromonas veronii HG8/10. Cluster analysis of individual banding patterns revealed that eight isolates identified as Aeromonas eucrenophila HG6 were dispersed over two well-separated AFLP clusters, suggesting the existence of a genotypic subdivision within this species. The remaining 24 unidentified isolates constituted a homogeneous AFLP cluster which was found to be most closely related to HG2. Possibly, these strains may represent a currently unknown HG within the A. hydrophila complex. In conclusion, this study clearly elucidates the taxonomic value of the AER094 database for the identification and classification of unknown aeromonads and further demonstrates the general applicability of AFLP-based libraries to determine genotypic relationships in other bacterial genera.