Abstract
Cholera bacteriophages have been classified into four distinct groups by Mukerjee (1963a). Of these, the group IV phages can differentiate Vibrio cholerae and V. eltor organisms (Mukerjee, 1963b) and are of practical importance. The hitherto unreported physiological and physico-chemical properties of the group IV cholera phage, 149, have been investigated by us and the results are presented below.
Cholera bacteriophage 149 was propagated on the host V. cholerae strain OGAWA 154 following in general the method of Hershey, Kalmanson & Bronfenbrenner (1943). The phage stock thus obtained usually contained about 1011 p.f.u./ml. as assayed by double agar layer technique (Adams, 1959). This phage yielded clear plaques of diameter between 0.5 and 1.5 mm. after 16 hr incubation at 37°. Longer incubation produced a surrounding halo. In all cases, bacteria were grown in nutrient broth (NB) containing, in 1 l. of distilled water: bactopeptone (Difco), 10g.; NaCl, 5 g.; beef extract (ACAS, Italy), 10 g.; pH 7.4.