A novel actinomycete, Streptomyces fugnipugnans sp. nov., with potent antifungal activity against Colletotrichum orbiculare

BACKGROUND: Cucumber anthracnose, which is caused by Colletotrichum orbiculare, significantly threatens the quality and production of crops. Chemical fungicides are frequently used to manage this disease, but increasing health and environmental concerns have highlighted the urgent need to develop sustainable biocontrol strategies. RESULTS: Actinomycetes were isolated from pine tree rhizosphere soil, and the NEAU-S77ᵀ strain was identified as a potent antagonist against C. orbiculare. Morphological, physiological, and biochemical analyses confirmed NEAU-S77ᵀ as a novel species, designated Streptomyces fugnipugnans sp. nov. Pot experiments showed that its spore suspension (1.0 × 10⁸ CFU/mL) significantly reduced the disease index of cucumber anthracnose from 57.3% to 14.1%, achieving a control efficiency of 80.3%. Fermentation optimization with cottonseed meal medium yielded a fermented supernatant with a pathogen inhibition rate of 71.9%. Whole-genome sequencing revealed a 10,269,260 bp genome (G + C content: 71.54%) encoding 8,495 genes. Functional annotation identified 390 genes related to secondary metabolite biosynthesis and 354 genes associated with antibiotic production. AntiSMASH analysis predicted 66 secondary metabolite biosynthetic gene clusters (BGCs), and comparison with the MIBiG database confirmed clusters encoding known antifungal compounds (e.g., 9-methylstreptimidone, mediomycin A, anisomycin, nigericin, bafilomycin B1). CONCLUSIONS: The novel strain S. fugnipugnans NEAU-S77ᵀ, isolated from pine rhizosphere soil, exhibits excellent biocontrol potential against C. orbiculare. Its high control efficiency, optimized fermentation performance in cottonseed meal medium, and rich repertoire of secondary metabolite BGCs (including those encoding known antifungal substances) highlight its prominent biocontrol activity and promising application in plant disease management.