Method for high-throughput antifungal activity screening of bacterial strain libraries

Authors: Palumbo, Jeffrey - Jeff; O Keeffe, Teresa

Submitted to: Journal of Microbiological Methods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2021
Publication Date: 8/21/2021
Citation: Palumbo, J.D., O'Keeffe, T.L. 2021. Method for high-throughput antifungal activity screening of bacterial strain libraries. Journal of Microbiological Methods. 189. Article 106311. https://doi.org/10.1016/j.mimet.2021.106311.
DOI: https://doi.org/10.1016/j.mimet.2021.106311

Interpretive Summary: Traditional methods to screen bacteria for antifungal activity involve radial growth assays, in which bacteria are spotted around the perimeter of an agar plate and the target fungus is plated in the center of the plate. After several days of incubation, antifungal activity is visualized as inhibition of the fungal growth outward from the center of the plate in the direction of the inhbiting bacteria. We developed a method to simplify and speed the screening of antifungal activity of thousands of bacterial isolates arrayed in 96-well culture plate format. In the improved method, spores of the target fungus are suspended in agar and poured into petri dishes. Once the agar has solidified, bacteria are transferred using a 48-tine manifold from half of a 96-well culture plate to the surface of a spore pour plate.Antifungal activity of individual bacterial colonies can be assessed within 48 hours, rather than 5 to 7 days with the radial growth assay, and can be visualized as inhibition of fungal growth and/or spore development.

Technical Abstract: We developed a high-throughput screen for antifungal phenotypes in which bacterial libraries in 96-well format are transferred to agar pour plates inoculated with spores of the target fungus. This method is an improvement over bacterial/fungal coculture plate methods that measure antifungal activity as inhibition of radial fungal growth.