Dual Culture Antagonism Assay v1

This protocol describes the dual culture antagonism assay used to evaluate the biocontrol potential of‘Candidatus Pseudomonas auctus’JDE115 against the phytopathogenic fungusAgroathelia rolfsii(syn.Sclerotium rolfsii). The assay was performed on potato dextrose agar (PDA) under both direct contact and non-contact conditions using sclerotia and hyphal plugs of the fungus. Multiple experimental setups were tested to assess bacterial–fungal interactions, with replicates conducted to ensure reproducibility. Antagonistic effects were evaluated through visual observation, photographic documentation, and radial growth measurements, followed by quantification of growth suppression. This standardized protocol provides a reproducible framework for assessing the antagonistic activity of bacterial biocontrol agents against soil-borne fungal pathogens.