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Ecology and Epidemiology

Motility and Chemotaxis of Erwinia herbicola and Its Effect on Erwinia amylovora. M. J. Klopmeyer, Former graduate research assistant, Department of Plant Pathology, University of Illinois at Urbana-Champaign 61801; S. M. Ries, Associate professor, Department of Plant Pathology, University of Illinois at Urbana-Champaign 61801. Phytopathology 77:909-914. Accepted for publication 25 November 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-909.

Optimum conditions for motility and chemotaxis of Erwinia herbicola (112Y) were determined by capillary assay. Cells grown at 29 C and suspended in motility medium containing phosphate buffer, adjusted to pH 7, were very motile. The optimum assay temperature tested was 37 C for motility and 29 C for chemotaxis. E. herbicola was attracted chemotactically to Jonathan apple nectar extract and to all fractions (organic acid, amino acid, and neutral and basic) of this extract. All amino acids tested, especially asparagine, histidine, and serine, were excellent chemoattractants. E. herbicola exhibited strong taxis to all sugars tested, but only to a few organic acids (malate and tartrate). High concentrations of cells of E. herbicola (> 2 × 10⁸ cfu/ml) in both the pond and the capillary of a capillary assay inhibited motility and chemotaxis of E. amylovora. Culture fluids of E. herbicola cells suspended in chemotaxis medium reduced the chemotactic response of E. amylovora toward malate. However, culture fluids of E. herbicola enhanced motility of E. amylovora.