Host Modification and Restriction with a Mycobacteriophage Isolated from a Pseudolysogenic Mycobacterium chelonei

SUMMARY: A pseudolysogenic Mycobacterium chelonei and its phage ø630 are described. Phage ø630 is the first mycobacteriophage reported to be resistant to the non-polar solvents chloroform, dioxan and diethyl ether. The phage had a latent period of 75 min, a rise period of 90 min and a burst size of 51. Evidence is presented for host modification and restriction. Phage ø630A, grown on host strain M. chelonei F-630 Rg, plated on the alternative host M. smegmatis ATCC607 with an efficiency of plating (e.o.p.) of 10-5. Phage ø630B, grown on host M. smegmatis, plated with an e.o.p. of 10-5 on the alternative host F-630 Rg. Phages ø630A and ø630B adsorbed equally well on their alternative hosts and on their indicator host strains. The progeny of plaques from initial platings on the alternative host, when grown in the alternative host, exhibited a marked reduction in e.o.p. on their original host.