Plasmids and phages in Bifidobacterium longum.

Fourteen strains of Bifidobacterium longum were tested for phage production with UV and mitomycin C as inducing agents. Only four strains released phage-like particles; of these four strains, two harbour plasmids, while two are apparently plasmid free. The induced phages have heads of dimensions ranging from 49 to 56 nm and tails from 76 to 268 nm long. No correlation is evident between any of the large variety of plasmids of B. longum and induced phages.