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Protein characterization reveals cell wall-degrading enzymes underlying antifungal activity of Bacillus velezensis against Botrytis cinerea and Ascosphaera apis

Year: 2025

Type: article

Abstract: Bacterial biocontrol agents offer environmentally sustainable alternatives to chemical fungicides for managing plant and livestock pathogen diseases. This study screened twelve bacterial isolates for antifungal activity against Botrytis cinerea and Ascosphaera apis using antagonistic assays. Seven isolates demonstrated significant inhibitory effects, with Bacillus velezensis SSH60 showing overall robust biocontrol efficacy against B. cinerea and A. apis . Cell-free supernatant concentrates from SSH60 showed dose-dependent antifungal activity, confirming that bioactive compounds are secreted extracellularly. In vivo validation using tomato fruits demonstrated practical biocontrol potential, with SSH60 crude protein extract reducing B. cinerea lesion size by 90 %. To identify the active antifungal components, extracellular proteins were fractionated by ammonium sulfate and fast protein liquid chromatography (FPLC). The 25–50 % ammonium sulfate fraction of SSH60 supernatant exhibited the strongest antifungal activity against both pathogens. Protein characterization identified three major bioactive enzymes: subtilisin or β-1,3-1,4-glucanase (∼27 kDa), α-amylase (∼60 kDa), and β-mannosidase (∼40 kDa). These enzymes target different fungal cell wall components through proteolytic degradation, polysaccharide hydrolysis, and mannoprotein disruption, representing a multi-enzyme biocontrol mechanism. Phylogenetic analysis confirmed SSH60 as B. velezensis . The activity of SSH60 against both plant and insect fungal pathogens represents a new approach to broad-spectrum biocontrol. This study demonstrates that B. velezensis SSH60 produces antifungal enzymes with potential for sustainable, dual-purpose biocontrol applications against economically important fungal pathogens in integrated disease management systems where both crop protection and pollinator health are priorities.

Source: Physiological and Molecular Plant Pathology

DOI: 10.1016/j.pmpp.2025.103028

Authors: Meng-Jie Lyu, Pearl Pei-Chun Chang

Institution: National Pingtung University of Science and Technology

Language: English

Topic: Plant-Microbe Interactions and Immunity

Subfield: Plant Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Zero hunger

Open Access status: hybrid

Estimated APC paid: $3,550