Alteration of phospholipid at various growth phases of Escherichia coli.

By inoculating E. coli B into the semisynthetic medium we conducted shaking culture, and observed alterations of the total phospholipid contents and the amounts of individual phospholipid components in various stages of growth. The results are briefly summarized as follows. 1. The total phospholipid content has been found to be greater during early culture period, while it decreases as the growth age advances. 2. Phosphatidyl ethanolamine gradually increase as the culture period approaches the stationary phase. 3. Phosphatidic acid and phosphatidyl glycerol decrease precipitously as growth age advances. 4. Cardiolipin shows the maximum content in the middle log phase when the growth rate is most speedy. ∗PMID: 4263559 [PubMed indexed for MEDLINE] Copyright c ©OKAYAMA UNIVERSITY MEDICAL SCHOOL Acta Merl. O:ayama 25, 255-260 (1971) ALTERATION OF PHOSPHOLIPID AT VARIOUS GROWTH PHASES OF ESCHERICHIA COLI Yasuhiro KANEMASA, Tieko YOSHIOKA, Hiroyuki ICHIKAWA and Kenichi TAKA! Department oj Microbiology, Okayama University Medical School, Okayama, japan (Director: Prof. j. T awara) Received jor publication, july 26, 1971 The lipid is an object of attention because the membrane delimiting the cell, and presumably conferring to it its characteristic of impermeability, is supposed to l:e constituted largely of lipid. As such, recently much interest is being focussed on the analysis and dynamic aspects of bacterial phospholipids, principal constituents of the cell membrane. In previous investigations of the composition of the phospholipids from E. coli B, the authors demonstrated the presence of cardiolipin, in addition to phos. phatidyl ethanolamine and phosphatidyl glycerol in the phospholipid frac. tion (1). Phospholipids, especially cardiolipin and phosphatidyl glycerol locali. zed exclusively in the cytoplasmic membrane, might reflect direct function of the membrane in the division process. We, therefore, think it useful to see whether any change in phospholipids occurs along with various culture conditions (2, 3, 4). In the present study alteration of phospholipid composition was investigated at various stages of growth. As a result it has been found that growth phase clearly gives considerable effects on the phos. pholipid composition and must be strictly controlled in investigation of phospholipids. MATERIAL AND METHODS Microorganism: E. coli B was grown in the semisynthetic medium at 37°0 with gentle shaking (1). In order to check the composition of phospholipid by the content of 32p in the individual phospholipids, 20 ,uc-30,uc [32PJ labeled H3P04 per ml was added from the start of incubation. Turbidity was measured periodically and sampled aliquot volume from medium at various stages. The cells were harvested by centrifugation at 4°0. Extraction and fractionation ofphospholipids: The precipitates were placed in 40 ml of chloroform-methanol (2: 1, v/v) and allowed to stand at room temperature for several hours. The extract was separa-