Computer aided assignment of motile Aeromonas strains to genospecies level by standard biochemical tests

A procedure is given for differentiation of motile Aeromonas spp. Based on nine to 12 biochemical properties it allows an assignment of isolated Aeromonas strains first to phenotypes and, in the second step, to hybridization groups (HGs) 1-13 as well as to the genotypically defined species Aer. allosaccharophila and Aer. encheleia. The computer aided classification is carried out according to the principles of numerical taxonomy. Using this differentiation scheme 23 Aeromonas strains, which were isolated from food, and two reference strains were speciated. A total of 16 strains were assigned to Aer. hydrophila, six strains to Aer. caviae and one strain to Aer. sobria. Of the 16 Aer. hydrophile strains, 11 were attached to HG 1, one to HG 2 and four could not be classified clearly as HG 3 or HG 1. All six Aer. caviae isolated were assigned to HG 5 and the Aer. sobria strain was ranked among HG 8. The reference strains were assigned to the same genotypes by this method than by DNA-DNA hybridization assays.