All phages were originally isolated from dairy environments, e.g. milk, sour milk, cheese, whey or
starter cultures. Most phages of group PO08 were grown on either Lactococcus lactis subsp. lactis (L.I.s.1.)
F7/2 or Bu2-60, which both show a restriction-modification-negative phenotype. Phages P221 BN,
P123BN and P114-4BN can only be grown on the Lactococcus lactis subsp. cremoris (L.1.s.c.) strains
indicated in the Table. Phages of the type POOl were, for historical reasons, grown on L.I.s.1. H42. This
strain is phenotypically identical to F7/2 but differs from F7/2 by the absence of a small cryptic plasmid.
Phages P109 and P127 were specific for L.1.s.c. strains. Phages P142ag, PO26 and PO87 can only be
grown on the indicated host strains.