Pectobacterium species which are facultative anaerobic bacteria are one of the most important causative agents which induce plant soft rot disease on many crops. They distributed in soil and cause crop losses in field and during storage. As Hamedan province is one of main places to produce potato and many area in this province are under potato cultivation the bacterium Pectobacterium atrosepticum cause serious disease on this plant. We collected diseased potato tubers from all area under potato cultivation and isolated the targeted green metallic bacteria on EMB medium. The pathogenicity of the isolated bacterial strains was confirmed on potato seedling and tubers. All tested strains were Gram negative, facultative anaerobic, bacilliform, peritrichus, catalase positive and oxidase negative. Results of this study showed that all potato fields and storages in Hamedan province were contaminated by Pectobacterium atrosepticum. The isolated bacterial strains were different in terms of pathogenicity and virulence power which show their longtime activity in this area. Genetic fingerprinting analysis of the tested strains via Rep-PCR technique using BOX and ERIC primers showed that they are diverse and ecologically distinct. Most of the bacterial strains were clustered based on their phenotypic features, pathogenicity, geographical distribution and genetic fingerprint.
