Characterization of two virulent Lactobacillus fermentum bacteriophages isolated from sour dough

Two different bacteriophages, FE5‐B1 and Z63‐B1, active against strains of Lactobacillus fermentum were isolated from a sample of sour dough of a regional wheat bread. They showed different host specificities when tested against 58 strains of obligately heterofermentative lactic acid bacteria, as well as differences in adsorption and one‐step growth kinetics. The burst size of FE5‐B1 was about 100 pfu cell −1 . This phage belonged to the A 1 morphotype of Myoviridae family, having an icosahedral head (83 nm diam.) and a sheathed contractile tail (170 nm in length). The phage consisted of five major structural proteins and had a genome of 86 kbp. Z63‐B1 showed a burst size of 10 pfu cell −1 and belonged to the B 1 morphotype or Siphoviridae family. Z63‐B1 had an isometric head (60 nm diam.) and a non‐contractile tail (160 nm in length), with eight major different structural proteins and a genome of 32 kbp.