海洋細菌の無機塩要求性に関する生理学的研究-IV

spheroplastsの生理学的諸性状

抄録

In the previous paper we had supposed that the type-specific salt requirements for the succinic acid oxidations of M (marine)-, MH (marine halophilic)-, TH (terrestrial halophilic)-and T (terrestrial)-types were present in the cell membrane. On the basis of that supposition, the formation of spheroplasts as a means of preparing the cytoplasmic membrane was attempted and several properties of the formed spheroplasts were studied in this paper. Four types of spheroplasts were formed by using penicillin G, which at 400 U/ml completely inhibited the biosyn-thesis of peptidoglycan in the cell wall in hypertonic media containing sucrose and MgCl₂. Cells inoculated into the media changed into spherical cells lacking a cell wall within several hours. Harvested spheroplasts indicated a sharp response to environmental conditions of various osmotic pressures, completely disrupting in distilled water, and best maintained in hypertonic solutions after removing penicillin G, peptone and yeast extract from the spheroplast-forming media. Constriction of the spheroplasts was observed microscopically in media supplemented with 0.25 _M, 0.50 _M, and 1.00 _M sucrose. When the nature of the spheroplasts was compared with that of the intact cells, the substrate-specificity of the spheroplast for the oxidations of sucrose, D-ribose, glucose, succinic acid, fumaric acid, L-arginine, L-leucine, L-glutamic acid, D, L-alanine and pyruvic acid were not altered.
The findings showed that the penicillin-induced spheroplasts were suitable material from which to prepare the cytoplasmic membrane and to investigate the mechanism of the type-specific salt requirements for succinic acid oxidation.