KBBC Medium

Pseudomonas syringae pv. syringae (Pss) is the causal organism of bacterial brown spot of beans. This bacterium is seed borne and therefore its detection on seeds is important. KBBC medium is a rather selective medium to detect Pss on seeds of beans. This medium is based on King’s B Medium (K5165), however in KBBC Medium boric acid (1.5 g/liter), cephalexin and nystatin are added. Nystatin is used to control fungi. As an alternative, cycloheximide, a more potent fungicide, can be used. KBBC is much more selective than MSP (M5167) and in general the recovery of Pss is smaller on KBBC than on MSP. Pspha, unlike Pss, will not grow on KBBC. Therefore, the chance of detection of Pss is higher when both complementary media are used.Detection of Pss is performed by the dilution plating of bacterial extract on KBBC and MSP. Then Pss-suspected isolates are transferred to KB medium. Finally, the identification of suspected colonies can be performed by a pathogenicity assay or PCR.Colonies of Pss on KBBC are 3-4 mm in diameter, flat, circular, translucent, creamy white and show blue fluorescence under UV light. This medium can also be used for the detection of seed borne Ps porri, Ps pisi and Ps tomato on seed of resp. leek, pea and tomato. For detailed information about Duchefa’s Phytopathological media have a look at our specialized brochure about this topic. Brochure can be found at the “Brochure section” at the home page of this website.