SPECIFIC DETECTION OF ERWINIA-CAROTOVORA SUBSP ATROSEPTICA WITH A DIGOXIGENIN-LABELED DNA-PROBE

A DNA probe specific for all four serogroups of Erwinia carotovora sub sp. atroseptica was selected from an EcoRI digest of a cloned library constructed with the combined genomic DNA from strains 6, 31, 196, and 198, which each represented one of the serogroups of E. c. atroseptic a. Specificity of the probe was initially tested against a panel of 40 E. carotovora strains representing serogroups I through XL. Subsequen tly hybridization of the probe, labeled with digoxigenin, was tested a gainst an additional 82 strains of E. carotovora. The probe hybridized to all strains previously identified as E. c. atroseptica on the basi s of biochemical and physiological tests, and it hybridized weakly wit h only one strain that was not a typical E. c. atroseptica strain. Thi s strain had been isolated from cauliflower in the United Kingdom. The probe hybridized with partially purified DNA extracted from enrichmen ts of potato periderm to which as few as 10 colony-forming units per m illiliter were added prior to incubation for 48 h. The hybridization r eactions to enrichment preparations were quantified by reading gray va lues from video images of the chemilumograms.