Biocontrol potential of Streptomyces lactacystinicus producing volatile organic compounds against postharvest anthracnose of chili pepper

Colletotrichum scovillei is a pathogen that causes anthracnose in pepper fruit, resulting in severe postharvest losses in pepper fruit. Volatile organic compounds (VOCs) produced by microorganisms are regarded as promising environmentally safe fumigants for controlling postharvest diseases. In this study, the Streptomyces lactacystinicus ZZ-84 strain was identified as exhibiting strong antagonistic activity against C. scovillei and effectively controlling anthracnose in pepper fruit. The VOCs generated by ZZ-84 significantly inhibited the mycelial growth and conidial germination of C. scovillei , disrupted mycelial morphology, altered cell membrane permeability, and induced oxidative stress. Transcriptomic analysis revealed that the VOCs primarily affected the metabolic pathways of C. scovillei , particularly those related to protein synthesis, cell membrane integrity, redox homeostasis, and energy conversion. The volatiles 2-methyl-1-butanol, sulphuric acid dibutyl ester, and 6-methyl-2-heptanone were identified as the main antagonistic compounds among the VOCs and exhibited strong antifungal activity against C. scovillei. Overall, strain ZZ-84 has the potential to serve as a microbial fumigation agent for controlling postharvest anthracnose in pepper.