CHARACTERIZATION OF TEMPERATE BACTERIOPHAGES OF LEUCONOSTOC-OENOS ANDEVIDENCE FOR 2 PROPHAGE ATTACHMENT SITES IN THE GENOME OF STARTER STRAIN PSU-1

The close relatedness between 17 Leuconostoc oenos bacteriophages, ind uced with mitomycin C from strains isolated in different geographic re gions, was inferred from their morphology, DNA homology and protein co mposition. The genome of all the phages had cohesive end termini and r anged in size from 36.4 to 40.9 kb. According to the restriction patte rns obtained by digestion with five enzymes, the phages were divided i n sis groups. Lysogenization of a spontaneous phage-cured derivative o f Leuc. oenos strain PSU-1 was achieved with 16 phages and the analysi s of the lysogens showed that the phage DNA integrates in the host chr omosome in one or two sites, The ntt B loci were located on the macror estriction AscI and NotI fragments of the recipient strain, A survey o f Leuc. oenos strains with a phage DNA probe confirmed the lysogenic n ature of several, but not all of the original phage hosts. These resul ts are discussed in the light of evidence for the instability of some lysogenic PSU-1 derivatives.