Abstract

Control of fungal plant diseases using antagonistic microorganisms is a promising strategy. This study aimed to identify and characterize an antagonistic microorganism effective against Mucor sp. MD7, a newly confirmed causative agent of leaf spot disease in strawberry in Da Lat, Vietnam. Koch’s postulate was used to confirm Mucor sp. MD7 as the causative agent. Antifungal activity screening was conducted through co-culture of 30 actinomycete strains with Mucor sp. MD7. The most potent strain was identified using macroscopic and microscopic characteristics, and 16S rRNA sequencing. Enzyme production, antifungal activity under various conditions, and in situ tests on strawberry leaves were performed to evaluate the antagonistic potential. Eighteen out of 30 tested actinomycete strains showed antagonistic activity, with Actinomycete CNXK31.2 being the most potent. This strain was identified as Streptomyces sp. CNXK31.2, showing 100% identity to Streptomyces fungicidicus. It produced chitinase, protease, and cellulase, causing swelling and degradation of Mucor sp. MD7 mycelia. The culture supernatant maintained antifungal activity at up to 80°C and pH 3.0–10.0. In situ tests demonstrated effective control of leaf spot disease. The findings of this study not only highlight the potential of Streptomyces sp. CNXK31.2 as an effective biocontrol agent but also contribute to achieving sustainable development objectives by promoting eco-friendly agricultural practices, safeguarding biodiversity, and enhancing food security.

Key words: Actinomyces Antifungal Leaf spot disease Mucor Strawberry Streptomyces