A bacteriophage of Bacillus subtilis which forms plaques only at temperatures above 50 C. II. Reduction of TSP-1-specific receptor sites on cells grown at 37 C or 45 C, and the temperature-dependent inactivation of replicating phage.

The adsorption of subtilisphage TSP-1 to Bacillus subtilis W168 was tested with cells grown at 37, 45, and 53 C. Kinetic data, electron micrographs, and quantitative measurement of the per cent phage adsorbed all indicated that irreversible adsorption occurs only with cells grown at 53 C. If TSP-1 was allowed to infect cells at 53 C, subsequent shifts to 37 C inhibited phage replication and resulted in the inactivation of plaque-forming units.