| 1. |
- Malmcrona-Friberg, Karin, et al.
(författare)
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Chemical changes in cell envelope and poly-β-hydroxybutyrate during short term starvation of a marine bacterial isolate
- 1986
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Ingår i: Archives of Microbiology. - 0302-8933. ; 144:4, s. 340-345
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Tidskriftsartikel (refereegranskat)abstract
- Qualitative and quantitative changes were observed in lipids, poly-β-hydroxybutyrate (PHB), and a cell wall peptidoglycan consitutent in a marine bacterial isolate during starvation for 24 h in an energy and nutrient-free medium. While the amount and composition of the membrane fatty acids fluctuated within the first hours of starvation, the total amount of fatty acids decreased during the starvation period. Furthermore, the ratio of monounsaturated to saturated fatty acids decreased and the proportion of short chain fatty acids increased. In the very early phase of starvation the bacteria contained PHB, which had been accumulated during the growth phase, but after 3 h no PHB was detected. Cells starved for phosphorus showed a different pattern as PHB was initially accumulated and did not decrease until 5 h of starvation. Synthesis of the cell wall amino acid d-alanine was initiated during the first phase of starvation. The effects of these changes on membrane fluidity and uptake of substrates as well as the use of fatty acids and PHB as energy resources during starvation are discussed.
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| 2. |
- Mårdén, Per, et al.
(författare)
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Physiological and morphological changes during short term starvation of marine bacterial islates
- 1985
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Ingår i: Archives of Microbiology. - 0302-8933. ; 142:4, s. 326-332
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Tidskriftsartikel (refereegranskat)abstract
- Three marine bacteria were examined for physiological and morphological changes in the initial phase of starvation. It was found that the starvation process was induced in a similar way irrespective of whether the cells were suspended in nutrient and energy free artificial seawater (NSS) or NSS supplemented with nitrogen and phosphorus. An initial phase of increased activity was consistent with a decreased response to added nutrients. Recovery from starvation exhibited the same response in both these starvation regimes, measured throughout the starvation period. Cells in nitrogen or phosphorus deprived starvation regimes, showed a high and rapid increased activity, followed by a delayed and more pronounced decline in respiratory activity. The initial phase of starvation also included a loss of poly-β-hydroybutyrate as observed by transmission electron microscopy (TEM). Two bacterial strains showed formation of small vesicles on the outer cell layer when examined by TEM. This formation and release of vesicles was related to the continuous size reduction during starvation survival. The results are discussed in terms of defining the mechanisms of initial cellular responses to nutrient deprivation.
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