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

Background Cucumber anthracnose, caused by Colletotrichum orbiculare , poses a significant threat to crop yield and quality. While chemical fungicides are commonly used for management, growing environmental and health concerns underscore the urgent demand for sustainable biocontrol alternatives. Results This study isolated actinomycetes from pine tree rhizosphere soil and identified strain NEAU-S77 ^T as a potent antagonist against C. orbiculare . Morphological, physiological, and biochemical analyses revealed that NEAU-S77 ^T represents a novel species, proposed as Streptomyces fugnipugnans sp. nov. The strain demonstrated strong, broad-spectrum antifungal activity. In pot experiments, its spore suspension (1.0×10⁸ CFU/mL) significantly reduced the cucumber anthracnose disease index from 71.4% to 14.1%, achieving an 80.3% control efficacy. Optimal fermentation was achieved using cottonseed meal medium, and the fermented supernatant exhibited 71.9% inhibition against the pathogen. Whole-genome sequencing revealed a large genome of 10,269,260 bp with a G+C content of 71.54% and 8,495 predicted genes. Functional annotation identified numerous genes involved in metabolism, secondary metabolite biosynthesis (390 genes), and antibiotic production (354 genes). AntiSMASH analysis predicted 66 secondary metabolite biosynthetic gene clusters (BGCs), among which comparative analysis with the MIBiG database identified clusters encoding known antifungal compounds, including mediomycin A, 9-methylstreptimidone, anisomycin, bafilomycin B1 and nigericin. Conclusions The novel strain Streptomyces fugnipugnans NEAU-S77ᵀ, isolated from pine rhizosphere soil, exhibited strong biocontrol activity against cucumber anthracnose, achieving 80.3% control efficacy in pot experiments. Cottonseed meal was identified as the optimal fermentation medium, and the derived metabolites demonstrated favorable stability. Genomic analysis revealed a substantial repertoire of protein-coding genes, including 390 associated with secondary metabolite biosynthesis and 354 linked to antibiotic production. AntiSMASH analysis predicted 66 BGCs, including those encoding known antifungal compounds such as mediomycin A and 9-methylstreptimidone. This prolific capacity for diverse secondary metabolite synthesis likely underpins the strain’s biocontrol activity and underscores its promising potential for application in plant disease management.