Differentiation of Erwinia carotovora subsp. atroseptica and carotovora by enterobacterial repetitive intergenic consensus (ERIC)-PCR

The biochemical and genetic characteristics of 11 Erwinia carotovora strains from potato were compared with those of reference strains, E. carotovora subsp. atroseptica (Eca) and E. carotovora subsp. carotovora (Ecc). On the basis of 26 phenotypic characters, four of the 11 strains showed intermediate characters between Eca and Ecc, and the rest of the strains were identified as typical members of Ecc. Current methods for differentiation of Eca and Ecc are both imprecise and time consuming. We have used enterobacterial repetitive intergenic consensus (ERIC)-PCR to differentiate the bacteria. Similarity of ERIC - PCR patterns within the Eca strains was very high, whereas within the Ecc group extensive genetic diversity was found. ERIC - PCR patterns of biochemically intermediate strains showed low similarity to those of Eca strains. An ERIC-PCR fragment from Eca type strain was isolated, and it was used as probe for Southern hybridization. The probe hybridized only with Eca strains. One reference strain (MAFF 301296) originally described as Ecc, was identified as Eca by ERIC-PCR analysis, and this result was confirmed by biochemical tests. ERIC-PCR analysis for differentiation of Eca and Ecc provides a relatively fast and sensitive alternative to routinely applied biochemical tests.