Microbe inoculation and dual culture assessment
The dual culture assay was performed in sterile 90 × 15 mm Petri dishes, containing YDCA or potato
dextrose agar (PDA; DifcoTM). Three replicate plates for each Paenibacillus and Xcc combination, and
three control plates for each Xcc isolate were set up for each agar. In a laminar flow cabinet, 0.1 ml of
a 1 × 109 CFU Xcc suspension was spread over the agar. After air-drying the inoculated plates in a
laminar flow cabinet for 1 h, the Paenibacillus isolates were spot-inoculated at four equidistant points
around the edge of the Petri dishes. The plates were then sealed and incubated at 25°C in the dark for
5 days (Figure 2.1).2