Isolation and Characterization of a Lysogenic Strain of Nocardia erythropolis

Abstract

A stable phage-carrying strain of Nocardia erythropolis was isolated from an infection with the nocardiophage φEC. Growth of the strain in phage-specific antiserum for 48 hr produced cured organisms at a frequency of about 0.5%. Spontaneous curing, determined by serial single-colony isolations, was less than 0.4%. The strain could not be infected by phage φEC nor by a closely related phage, φC, although the cells were able to adsorb these phages. In cell populations, a frequency of 2.5 × 10 −4 cells spontaneously induced. The growth rate of the strain was comparable to that of the uninfected wild-type N. erythropolis. Ultraviolet irradiation or treatment with mitomycin C induced the strain to produce larger numbers of phage. It was concluded that the isolated strain was lysogenic.