Electron microscopy of phages liberated by megacin A producing lysogenic Bacillus megaterium strains

Mitomycin C was added at fairly high concentration (5-10 mug/ml) to exponentially growing cultures of selected strains of Bacillus megaterium. Lysis of the bacteria followed, associated by liberation of phage and megacin A production. In contrast, a low concentration (0.5 mug/ml) of mitomycin induced only megacin A production. Electron microscopic examination of the lysates induced by 5-10 mug/ml of mitomycin in 19 strains of B. megaterium showed them all to contain phages; most of the strains proved polylysogenic. Their lysates contained distinct complete phages of different structures and dimensions. A few strains released defective phage particles. The significance of the electron microscopic findings is discussed in relation to megacinogeny.