GENOTYPIC AND CHEMOTAXONOMIC DESCRIPTION OF 2 SUBGROUPS IN THE SPECIES AEROMONAS-EUCRENOPHILA AND THEIR AFFILIATION TO AEROMONAS-ENCHELEIA AND AEROMONAS DNA HYBRIDIZATION GROUP-11

We describe the results of a polyphasic taxonomic study that aimed to elucidate the genotypic heterogeneity observed previously among the ei ght original reference strains of the species Aeromonas eucrenophila. In addition, this investigation also included representatives of the n eighbouring taxa Aeromonas encheleia and Aeromonas DNA hybridization g roup (HG) 11, as well as a collection of 14 mainly aquatic Aeromonas s p. isolates which were previously found to be closely related to A. eu crenophila. All 28 strains were subjected to ribotyping, whole-genome analysis by AFLP fingerprinting, electrophoretic profiling of soluble cellular proteins, and gas-liquid chromatographic analysis of cellular fatty acid methyl eaters. Cluster analysis of the data uniformly conf irmed our previous findings and delineated two well-separated subgroup s in A. eucrenophila. Subgroup I was represented by the type strain of this species (LMG 3774) and four other original reference strains, of which one strain (LMG 13687) displayed a somewhat atypical fatty acid profile. This subgroup could be extended by the inclusion ai lour Aer omonas isolates that were unambiguously classified in A. eucrenophila subgroup I. The three remaining reference strains originally described as A. eucrenophila were allocated to subgroup II, but could not be di fferentiated from members of A. encheleia and HG11. Consequently, a cl ear-cut classification of poorly identified or unknown Aeronomas isola tes into one of the latter three taxa was not possible on genotypic or chemotaxonomic basis. In conclusion, the current report has provided substantial polyphasic evidence to support an emended description of t he species A. eucrenophila. Moreover, the high genotypic and chemotaxo nomic resemblance of A. eucrenophila subgroup LI, HG11, and A. enchele ia revealed in this study suggests that these three groups may actuall y belong to the same genomic species.