Thermal Resistance and Antifungal Properties of Bacillus amyloliquefaciens KW21

Rhizoctonia solani is a destructive soil-borne pathogen causing substantial yield losses in diverse crops worldwide. To develop sustainable alternatives to synthetic pesticides, a thermally resistant Bacillus amyloliquefaciens strain, KW21, was isolated from agricultural and forest soils in Korea. KW21 was selected for its antifungal activity against R. solani and its ability to retain this activity after high-temperature exposure. 16S rRNA gene sequencing and phylogenetic analysis confirmed > 99% similarity to B. amyloliquefaciens . In vitro assays demonstrated consistent inhibition of R. solani growth. Thermal resistance testing revealed D-values of 47.6 h at 110°C, 8.3 h at 120°C, and 1.13 h at 130°C, with Z-values of 13.2°C and 11.5°C.