Cultivation of Streptomyces scabiei EF-35

The pathogenic Streptomyces scabiei strain EF-35 was isolated from a common scab lesion from a potato tuber collected in Canada [2 (link)]. Bacterial inoculum was prepared as follows. Approximately 10⁸ spores were added to 25 mL of yeast malt extract (YME, 4 g/L of glucose, 4 g/L of yeast extract and 10 g/L of malt extract; BD, Detroit, MI, USA) and incubated with shaking (250 r/min) for 48 h at 30°C. The bacterial culture was then centrifuged (2500 × g) for 5 min and the supernatant discarded. Bacterial pellets were subsequently resuspended in 5 volumes of 0.85% NaCl. In all experiments, an inoculum of 200 μL was transferred to 50 mL of minimal medium supplemented with 0.1% suberin and 0.05% casein hydrolysate (Sigma, St. Louis, MO, USA), or casein hydrolysate only. Suberin was extracted from potato tubers according to Lerat et al. (2012) [6 (link)]. Three culture replicates for each medium were incubated with shaking (250 r/min) at 30°C for 1, 3 or 5 days.