BISC209: Agar Overlay
Agar Overlay Pour Plates
In this technique a small amount of soft agar is added to the surface of an agar plate. It is useful when dispersing organisms inoculated into the soft agar to support an even lawn of growth. Most often this technique is used for viral assays or in antibiotic sensitivity assays.
materials: prepoured agar plates, Soft agar pours in hot water bath (tubes with about 3-5ml of melted agar)
Generally, Serial Dilution preceeds the inoculation of soft agar pours. Once inoculated the soft agar is poured over the surface of the agar plates. Plates are incubated and plaques of viruses or colonies to be enumerated are counted. The number or plaque forming units (PFU) (or enumerated colonies (CFU) are calculated as number/ml of original using the formuala:
