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|Title:||Motility and Chemotaxis of Erwinia Herbicola and Its Effect on Erwinia Amylovora (Biological Control, Phytobacteriology, Fire Blight)|
|Author(s):||Klopmeyer, Michael Jon|
|Department / Program:||Plant Pathology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Agriculture, Plant Pathology|
|Abstract:||Optimum conditions required for motility and chemotaxis in Erwinia herbicola (112Y) were determined by the capillary assay. Actively motile cells were selected from the periphery of swarming colonies grown on soft agar (0.25%) modified Emerson's medium plates minus the ingredient nutrient broth. The optimum growth temperature for producing motile cells was 29 C. Cells were still motile at assay temperatures of 37 C. Good motility was observed when E. herbicola cells were suspended in a motility medium consisting of 10('-2)M K(,2)HPO(,4)-KH(,2)PO(,4) buffer, 10('-3)M ethylene-diamine tetraacetic acid (EDTA) and adjusted to pH 7. Motility occurred without an exogenous energy source; however, mannitol at 10('-2)M, slightly enhanced motility after induction in modified Miller and Schroth's medium.
Chemotaxis, using Jonathan apple nectar extract as an attractant, was also dependent upon temperature and assay time. The optimum chemotaxis assay temperature was 29 C, and an incubation period of 40 min was optimal for maximum accumulation of bacteria per capillary. The presence of magnesium chloride in the motility medium did not enhance chemotaxis.
Erwinia herbicola was attracted towards Jonathan apple nectar extract (10('-1) dilution) and to all fractions of this extract. It exhibited good taxis to many sugars, most amino acids and three organic acids tested. Threshold concentrations were determined for selected attractants. There appeared to be many different chemoreceptors for these attractants as determined by competition experiments. The chemotactic response to many different compounds was similar using a different strain of E. herbicola (Tr(,2)#3).
The presence of high concentrations of E. herbicola cells in both the pond and capillary inhibited motility and chemotaxis of E. amylovora (#110). Culture filtrates (CF) of E. herbicola also reduced the chemotactic response of E. amylovora towards malate, however CF enhanced motility of E. amylovora. Inhibition of E. amylovora chemotaxis towards malate by E. herbicola may be the result of malate utilization by E. herbicola during the capillary assay thus reducing the chemotactic response of E. amylovora. Two different strains of E. herbicola could utilize malate as a sole carbon and energy source.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.
|Date Available in IDEALS:||2014-12-15|