An investigation of membrane fluidity changes during sporulation and germination of Bacillus megaterium K.M. measured by electron spin and nuclear magnetic resonance spectroscopy
1. Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW U.K.;2. Environmental Safety Division, Unilever Research, Colworth Laboratories, Sharnbrook, Bedford, MK44 1LQ U.K.
Abstract:
Changes in membrane and macromolecular fluidity which may accompany the differentiation processes of sporulation and germination in Bacillus megaterium K.M. are examined by electron spin and nuclear magnetic resonance spectroscopy. No change in membrane lipid fluidity is observed in isolated forespores up to stage VI. Between stage VI and release of mature spores, the ESR spectrum of doxylstearic acid spin labels becomes polycrystalline. This change in spectral fluidity is completely reversed during germination and is paralleled by the rapid release of Ca2+ from the spore. NMR studies also show that the mature spore has reduced macromolecular mobility and an increased non-exchangeable water pool compared with vegetative cells.