First Report of the Purple Variant of Curtobacterium flaccumfaciens pv. flaccumfaciens, Causal Agent of Bacterial Wilt of Bean, in Canada

Bacterial wilt of bean (Phaseolus vulgaris L.) caused by the yellow and orange variants of Curtobacterium flaccumfaciens pv. Flaccumfaciens (Hedges) Collins & Jones was found in western Canada in 2002 (1). A purple variant was found in a pooled sample of discolored cull seeds of great northern bean (cv. US1140) from a crop grown near Bow Island, Alberta, Canada in 2005. Bacterial colonies isolated from purple seed using modified Burkholder's agar (MBA) (3) were convex, glistening, and smooth edged with blue pigment diffusing into the medium. Three isolates (V154, V155, and V254) were identified with conventional tests (2), carbohydrate oxidation (GP Microplates, Biolog Inc., Hayward, CA), and cellular fatty acids (CFA) (MIDI, Inc., Newark, DE). All were grampositive, motile, aerobic rods with yellow colonies producing extracellular blue pigment on MBA when grown at 20 ± 2°C. Bacterial isolates grew at 27°C but grew weakly at 37°C. They were positive for catalase and hydrolysis of hippurate and indoxyl acetate and negative for urease, gelatin liquification, and oxidase. CFA profiles were approximately 48% 15:0 anteiso, 40% 17:0 anteiso, 7% 16:0 iso, and 3% 15:0 iso; with 17:1 anteiso A variable but