Ultrastructure and Host Specificity of Bacteriophages of Streptococcus cremoris, Streptococcus lactis subsp. diacetylactis , and Leuconostoc cremoris from Finnish Fermented Milk “Viili”

Abstract

milk product, has a firm but viscous consistency. It is produced with traditional nesophilic mixed-strain starters, which have various stabilities in dairy practice. Thirteen morphologically different types of phages were found in 90 viili samples studied by electron microscopy. Ten of the phage types had isometric heads with long, noncontractile tails, two had elongated heads with long, noncontractile tails, and one had a unique, very long elongated head with a short tail. Further morphological differences were found in the tail size and in the presence or absence of a collar, a baseplate, and a tail fiber. To find hosts for the industrially significant phages, we examined the sensitivities of 500 bacterial isolates from starters of the viili. Seven of the phages attacked Streptococcus cremoris strains, three attacked S. lactis subsp. diacetylactis strains, and four attacked Leuconostoc cremoris strains. Some phages differed only in their host specificity. Hosts were not found for 4 of the 13 morphological types of phages.

Characterization of starter lactic acid bacteria from the Finnish fermented milk product viili

“…lactis is not necessarily a minor strain in viili starters, but may in fact be a dominating lactococcal strain. In the article of Saxelin et al. (1986) the lactococcal (streptococcal) strains of the starter studied were defined as L. lactis subsp.…”

Characterization of four new Lactococcus lactis bacteriophages isolated from dahi whey

“…1976; Henning et al . 1986; Saxelin et al 1986). Dahi, an analogue to yogurt, is a popular fermented milk product of the Indo‐Pak subcontinent.…”

Characterisation of four Leuconostoc bacteriophages isolated from dairy fermentations

“…Although Leuconostoc strains are present iu mixed mesophilic starter cultures [l], there are few reports of phases from dairy Leuconostoe strains. Sozzi et al [2] isolated a phage of Leuconostoc mesenteddes from dairy products and recently Leuwnostuc cremoris phages from Finnish fermented milk have been described [3]. These reports have been restricted mainly to a morphological description of the phage and to date there has been a lack of information particularly at the genetic level relating to this group.…”