Ascamycin is a 5-O-sulfonamide ribonucleoside antibiotic produced by Streptomyces sp. JCM9888. Ascamycin has a selective antibacterial activity against Xanthomonas species with MIC values of 0.4 µg/mL, 12.5 µg/mL and 12.5 µg/mL for Xanthomonas citri, Xanthomonas oryzae and Mycobacterium phlei, respectively[1][2][3].