Please, use the host strain recommended for a particular phage (see our homepage). DSMZ will not
guarantee for successful phage propagation when other strains are used as hosts. Phage stocks can
be prepared directly from phage suspensions, or by floating plaque-containing agar plates with phage
buffer. Performing lysis is possible by using liquid cultures or on plates. In case of plates, they can be
shaken carefully on a plate shaker for several hours in order to get a high titre, or the soft agar layer
can be scraped off under sterile conditions. In case of liquid lysis, the culture should be observed
because of the development of possibly phage-resistant bacterial cells overgrowing the culture. Agar
and bacterial debris should be sedimented by centrifugation. A filtration through 0.45 µm membrane
filters is recommended. Upon severe loss of titre, even from a single plaque a phage suspension can
be prepared by using a sterile pasteur pipette for recovery of the plaque and subsequent suspension in
a few drops of phage buffer. High titre phage stocks can be prepared with the agar layer method: 5 mL
medium are added to a plate with confluent lysis. Use the dilution plates for examining plaque
morphology.