Characterization of lactococcal bacteriophages isolated from Slovenian dairies

This is the first study on lactic acid bacteria bacteriophages isolated from dairy plants in Slovenia. Over a period of 2 years, thirteen lactococcal phages were isolated from the whey samples taken in three dairy plants. Phages were characterized by morphological properties, host range, restriction patterns, genome size and similarity of phage protein genes. All phages belonged to the Siphoviridae family. Five phages had prolate heads (52–61 × 40–52 nm) and 85–120 nm long non-contractile tails (morphotype B2). Eight phages had small isometric heads (46–63 nm in diameter) and long non-contractile tails (morphotype B1). The phages with the prolate heads showed a broader host range than the small isometric-headed phages. The genome sizes of prolate phages were estimated between 15.9 and 16.3 kb while the genome sizes of small isometric-headed phages were between 20.0 and 39.9 kb. Based on DNA restriction patterns, genome sizes and multiplex PCR analysis prolate phages were classified into the c2 group and were similar to the phage type c6A while all of the phages with small isometric heads were found to be related to the phage species 936.