Partial characterization of a new C3-type capsule-dissolving phage of Streptococcus cremoris.
A viscous, ropy, sour milk product, called 'viili,' is produced in Finland. Capsule-forming strains of Streptococcus cremoris are the typical starters for this product. Occasionally fermentation fails and results in a non-ropy clot. The reasons for these failures, however, are obscure. In one batch of spoiled 'viili,' a new C3-type bacteriophage, termed KSY1, was isolated. The head of the phage was about 230 nm long and about 50 nm wide and the tail was 35 nm long and carried a complex collar structure. Upon infection of a number of encapsulated cultures of S. cremoris with KSY1, the cocci, though not serving as a host of the phage, lost their capsules. A capsuleless strain, S. cremoris 249, served as a host. The latent period was about 150 min and the average burst size 80. The bouyant density of KSYI1 was 1.436 g/cm3.
D000818:Animals; D001435:Bacteriophages / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure*; D002417:Cattle; D002473:Cell Wall / Q000378:metabolism; D005516:Food Microbiology; D013294:Lactococcus lactis / Q000378:metabolism; D008892:Milk / Q000382:microbiology*; D013045:Species Specificity; D013291:Streptococcus / Q000378:metabolism; D014779:Virus Replication