Multiplication of bacteriophage P22 in penicillin-induced spheroplasts of Salmonella typhimurium

Abstract

The spheroplasts of Salmonella typhimurium (LT2) prepared by treatment with penicillin were capable of adsorbing phage P22 C₁. The normal multiplication of the phage took place, although the burst size was reduced to one-fourth of that in intact cells. Rate of incorporation of 14C-thymidine into spheroplasts was increased severalfold on phage infection. Multiplication of C⁺ also took place, but no lysogeny could be established in spheroplasts. Furthermore, spheroplasts prepared from cells lysogenized with wild-type phage, LT2 (C⁺), and a temperature-inducible C₂ mutant, LT2(tsC₂), were not inducible. Unlike normal cells, both mitomycin C and actinomycin D interfered with the phage multiplication in spheroplasts. The spheroplast system offers great advantages in the study of the synthesis of nucleic acids and proteins in phage-infected LT2.