Whole genome analysis, thermal and UV-tolerance of Lactococcus phage BIM BV-114 isolated from cheese brine.

Lactococcus phages that belong to the genus Ceduovirus are among the three most frequently isolated phage groups infecting Lactococcus lactis starter strains in dairy plants. In this study, we characterized virulent Lactococcus phage BIM BV-114 isolated from industrial cheese brine in Belarus and identified as Ceduovirus. The bacteriophage demonstrated a relatively short lytic cycle (latent period of 23 ± 5 min, lysis time of 90 ± 5 min), high thermal stability (inactivation after 7 min at 95 °C in skimmed milk) and tolerance to UV radiation (inactivation time - 15 min), indicating adaptation for better persistence in dairy facilities. The genome of the phage BIM BV-114 (21 499 bp; 37 putative open reading frames) has a similar organization to that of other Ceduovirus phages. RLf1_00140 and RLf_00050 gene products, found in the early genes region, may be involved in the sensitivity of phage to the lactococcal abortive infection mechanisms AbiV and AbiQ, respectively. Furthermore, nucleotide deletion, observed in the middle region of the gene encoding putative tape measure protein (RLf1_00300), is possibly responsible for increased thermal tolerance of phage BIM BV-114. Together, these findings will contribute to a better knowledge of virulent Lactococcus phages and the development of effective methods of their control for dairy technologies.