Scabicidin from Insect Gut Streptomyces Effectively Controls Potato Scab by Targeting DNA Gyrase

Potato scab, caused by multiple Streptomyces species, is a major soil-borne disease with no effective chemical control. In this study, we isolated Streptomyces niveus NEAU-TZZ3 from the gut of Diestrammena japonica and identified its principal antibacterial metabolite as scabicidin. This compound exhibited potent inhibitory activity against six Streptomyces pathogens responsible for potato scab, with EC50 values of 0.056–0.84 μg/mL, substantially lower than those of the commercial bactericide zhongshengmycin. In pot and field trials, scabicidin provided dose-dependent control efficacy, reaching 81.7% and 52.03%, respectively. Mechanistic studies revealed that scabicidin targets the DNA gyrase GyrB subunit in Streptomyces scabies, competitively inhibiting ATP binding and disrupting DNA supercoiling. These findings establish scabicidin as a promising natural antibiotic from an insect-associated Streptomyces for effective potato scab management.