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Aminopeptidase Profiles of Virulent and Avirulent Erwinia amylovora and Erwinia herbicola. John L. McIntyre, Department of Plant Pathology and Botany, Connecticut Agricultural Experiment Station, New Haven 06504; D. Huber(2), J. Kuc (3), and E. B. Williams(4). (2)(4)Department of Botany and Plant Pathology, Purdue University, Lafayette, Indiana 47907; (3)Department of Plant Pathology, University of Kentucky, Lexington 40506. Phytopathology 65:1206-1212. Accepted for publication 13 May 1975. DOI: 10.1094/Phyto-65-1206.

Five isolates of Erwinia amylovora, two isolates of avirulent E. amylovora and three isolates of E. herbicola, an avirulent Erwinia sp., appear related on the basis of aminopeptidase profiles. The profiles were derived from the hydrolysis of 27 aminoacyl-β-naphthylamides and β-naphthylamides of phosphate, sulfate and acetate after incubation periods of 4 and 24 hours. Differences in hydrolysis were not apparent in replicate treatments and differences in hydrolysis by isolates within each of the two species were ≥ 4% indicating that aminopeptidase profiles offer a rapid, reproducible means of microbial identification to supplement morphological and cultural criteria. Qualitative and quantitative differences in the hydrolysis of several aminoacyl-β-naphthylamides were evident among the three bacteria. Virulent E. amylovora hydrolyzed glycyl- and alanyl-β-naphthylamides, whereas neither avirulent E. amylovora nor E. herbicola hydrolyzed glycyl-β-naphthylamide. Erwinia harbicola hydrolyzed alanyl-β-naphthylamide less readily than did virulent E. amylovora. Avirulent E. amylovora did not hydrolyze alanyl-β-naphthylamide. Avirulent E. amylovora and E. herbicola hydrolyzed β-naphthylamides of phenylalanine and tyrosine more rapidly than did virulent E. amylovora.