Screening for Antibacterial, Antifungal, and Anti quorum Sensing Activity

The plate-hole diffusion assay is an invaluable screening tool to evaluate the antibacterial potential of natural products. It relies on the diffusion of test material from pre-cut wells through agar seeded with bacteria. Samples that are capable of inhibiting bacterial growth will produce a clear zone surrounding their well. For the evaluation of antifungal activity of natural products, we describe the broth microdilution method. This assay is performed using a 96 well microtiter tray containing fungal inoculum, test medium and natural product material. Samples demonstrating antifungal activity will prevent any discernible growth as detected visually. A disk diffusion assay, utilizing the pigmented indicator strainChromobacterium violaceum, is described here for the screening of natural products for anti quorum sensing activity. Inhibition of quorum sensing results in growth of non-pigmented bacteria.

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