Biodiversity of bacteriophages infecting Lactococcus lactis starter cultures

Abstract

In the current study, we characterized 137 Lactococcus lactis bacteriophages that had been isolated between 1997 and 2012 from whey samples obtained from industrial facilities located in 16 countries. Multiplex PCR grouping of these 137 phage isolates revealed that the majority (61.31%) belonged to the 936 group, with the remainder belonging to the P335 and c2 groups (23.36 and 15.33%, respectively). Restriction profile analysis of phage genomic DNA indicated a high degree of genetic diversity within this phage collection. Furthermore, based on a host-range survey of the phage collection using 113 dairy starter strains, we showed that the c2-group isolates exhibited a broader host range than isolates of the 936 and P335 groups.

Lactococcus Ceduovirus Phages Isolated from Industrial Dairy Plants—From Physiological to Genomic Analyses

“…The sequenced phages show a preference for strains with type C CWPS, which is in line with previous reports on Ceduoviruses [10]. Based on this analysis, they were grouped into two types (i) phages infecting hosts with a specific CWPS type (B-for phages Am4 and p6/4, and C-for phages A3 and 12) and (ii) those which lyse hosts with different saccharidic receptors (six remaining phages).…”

“…Phages belonging to the Ceduovirus group are the second most persistent group of lytic Lactococcus phages in dairy plants worldwide. Biodiversity studies have shown the dominance of lytic Ceduovirus phages in whey samples only in several countries (e.g., Canada, Germany, Russia, Belarus, and the Czech Republic) [10,54,55]. This observation seems intriguing given the fact that Ceduovirus phages have been repeatedly described to have a much wider host range compared to Skunavirus phages, and it would be expected that they would encounter a permissive strain more frequently and spread in the environment more easily [10,33,56,57].…”

“…This stands in strong contrast to the well-characterized and abundantly sequenced Lactococcus Skunavirus (formerly 936-type or sk1virus) type [4][5][6]. Until now, less than 40 complete genome sequences of Ceduovirus phages were available in databases [7][8][9][10][11][12][13]. Based on previous studies, involving genome sequencing, Ceduoviruses were determined to represent a genetically similar phage group.…”

“…Initiation of Ceduovirus phage infection is described as a two-step process relying on (i) reversible adsorption to the bacterial cell wall polysaccharide (CWPS) followed by (ii) irreversible binding to a proteinaceous receptor [19][20][21]. A study by Oliveira and co-workers [10] on 21 Ceduovirus phages determined their strong preference for bacterial hosts with the type C CWPS genotype. This suggests that although the interaction with the host CWPS is reversible, it may be crucial in the initial step of infection, ensuring a high rate of phage adsorption and effective propagation.…”

Complete Genome Sequences of 28 Lactococcal Bacteriophages Isolated from Failed Dairy Fermentation Processes

“…B acteriophage infection of Lactococcus lactis strains, which are used as starter cultures in dairy fermentation processes, is one of the main causes of fermentation failure and causes great economic losses for dairy industries (1,2). Bacteriophages infecting L. lactis have been divided into 10 species (3), and those belonging to species c2, 936, or P335 are more commonly encountered in dairy plants (4,5). However, isolates belonging to other species have also been reported to cause dairy fermentation halts (6)(7)(8)(9)(10).…”