Characterization of phage isolates from a phage-carrying culture of Leuconostoc oenos 58N

Summary During large-scale cultivation of Leuconostoc oenos strain 58N, growth inhibition was detected and attributed to the presence of the virulent phage P581. To determine if this phage originated from a temperate phage, L. oenos 58N was exposed to mitomycin C, and this treatment led indeed to release of phages (P58II). Further examination of the lytic potential of phages P581 and P58II revealed that these two phages were able to lyse the same strains of L. oenos with the exception of the original host strain, which was only sensitive to P581. Results of DNA/DNA hybridization experiments failed to show homology between the DNA of phage P58II and the chromosomal DNA of L. oenos 58N. A phage-free culture of L. oenos 58N could be obtained after repeated subculture. These results indicate that the original L. oenos 58N was in a special type of phage-carrier state. Phages P58I and P58II were compared on the basis of morphology, lytic spectra, restriction enzyme analysis, DNA homology, genome size and protein structure and proved to be identical. It is assumed that P58I arose from the phage-carrier culture of L. oenos 58N and became virulent by some mutational event.Offprint requests to: E. K. Arendt