Date of Award
Doctor of Philosophy
The biochemical and biophysical properties of Bacillus megaterium KM spore and cell membranes were investigated. Spore inner and outer membranes have been prepared from coat-stripped spores and solubilized spore coat proteins, respectively.;The spore inner and cell membrane phospholipids are similar, except for a decrease in phosphatidylethanolamine in late vegetative state or early sporulation and a decrease in phospholipid content to one-half that of the cell membrane early in spore formation (Stage III). The unique red carotenoid of the inner membrane appears later in B. megaterium KM (Stage V) than in B. megaterium QM B1551 (Stage III-IV). The spore inner and cell membranes have distinct protein profiles, however both have similar penicillin-binding proteins.;Although the extracted phospholipids have similar electron spin resonance spectra and fluidity profiles, the spore inner membrane is more viscous than the cell membrane. This increased viscosity could reflect a more extensive lipid-protein interaction in the spore inner membrane. Also the changed environment of the inner membrane in the intact coat-stripped spore, i.e. dehyrated core and high Ca('+2) content, could affect the membrane viscosity.;There is little phospholipid in the solubilized spore coat proteins, however the significant amount of lipid-extractible material indicates the presence of the outer membrane and a switch to synthesis of neutral lipids during sporulation. Most outer membrane lipids are extractible only after solubilization or disruption of the coat proteins. This fact and the demonstration of small molecular weight (< 20) proteins extracted with the outer membrane lipids indicates a strong lipid-protein interaction.;The solubilized spore coat and outer membrane have 3 or 4 major proteins. Certain of these proteins can be preferentially solubilized, suggesting these may be outer membrane proteins. Treatment of spores with p-chloromercuribenzoate alters the coat protein profile, which might explain the concomittent loss in germination specificity.;This research has expanded the knowledge of the spore and cell membranes of B. megaterium KM and demonstrated severe limitations for using integuments as a source of outer membrane components due to contamination by inner membrane components. The existence of an outer membranous component in mature spores has been substantiated such that its function in germination must now be considered.
Elmes, Mary Lynn, "A Comparison Of The Membranes Of Bacillus Megaterium Spores And Cells" (1983). Digitized Theses. 1295.