Bacteriophage Plaque-count Assay and Confluent Lysis on Plates without Bottom Agar Layer

WITH so much research being carried out on bacterio-phage, improvements to simplify and save time in the routine techniques of assay and preparation would be of great value. Having spent considerable time on preparation of ‘bottom’ agar plates for the agar layer assay by the plaque count method1,2 and for high-titre bacterio-phage stock preparation on a large number of plates by the confluent lysis method3, we investigated the possibility of saving time by using plates without ‘bottom’ agar for assay and stock preparation.