Preparation and partial characterization of a Lactobacillus lactis bacteriophage

High-titer lysates of a bacteriophage active against Lactobacillus lactis were prepared from liquid cultures as well as from areas of confluent lysis in soft-agar overlayers. Phage concentration and purification were accomplished by means of polyethylene glycol precipitation, differential centrifugation, and cesium chloride gradient centrifugation. The buoyant density of this phagein cesium chloride was 1.4795 g/ml. Characterization of phage growth cycle by one-step growth experiments under optimal conditions showed that the latent period was about 120 min, that the rise period lasted approx. 130 min, and that the average burst-size was about 80.Abbreviations p.f.u. plaque forming units - m.o.i. multiplicity of infection - PEG polyethylene glycol - SSC standard saline citrate solution