| Author/Editor | Turk, Martina | |
| Title | Vpliv hiperslanega okolja na sestavo in fluidnost membran halofilnih črnih kvasovk | |
| Type | monografija | |
| Place | Ljubljana | |
| Publisher | Medicinska fakulteta | |
| Publication year | 2000 | |
| Volume | str. 72 | |
| Language | slo | |
| Abstract | Certain microorganisms are capable of living in hypersaline environments. In order to survive in such extreme environments a broad variety of biochemical adaptations have evolved to allow the eukaryotes and prokaryotes to cope with osmotic and ionic stress, temperature changes, various light environments and variations in concentrations of oxygen and sulfide. Besides synthesis of compatibile solutes, changes in the composition, fluidity and permeability of the membranes may play an important role in the adaptations to hypersaline conditions. The influence of high concentrations of NaCI on the membrane lipid composition and membrane fluidity was studied within my thesis. Sterols, glycerophospholipids, total fatty acids and fatty acids, isolated from glycerophospholipids were investigated in black yeasts Hortaea werneckii, Phaeotheca triangularis, Trimmatostroma salinum and halotolerant Aureobasidium pullulans, and their composition compared to mesophilic yeast Saccharomyces cerevisiae. Ergosterol was the major sterol component in all investigated black yeasts. Although sterol profiles of black yeasts slightly changed as a response to elevated NaCI concentrations, these changes were far less pronounced than in mesophilic S. cerevisiae, were high NaCI concentration caused a decrease in ergosterol portion and an increase in squalene and zymosterol together with increase in total sterol amount. This results point to different regulation of sterol biosynthesis in black yeasts as a response to high salinity. The major phospholipid species in black yeasts were phosphatidylcholin and phosphatidylethanolamine. Dominant phospholipids of investigated black yeasts were characterised by a high percentage of C18:2 delta9,12 fatty acid present in S. cerevisiae only in traces. In all studied black yeasts we also identified traps isomere of C18:2 delta9,12 fatty acid. Membrane fluidity was higher in black yeasts than in S. cerevisiae. (Abstract truncated at 2000 characters.) | |
| Descriptors | YEASTS CULTURE MEDIA SODIUM CHLORIDE MEMBRANE FLUIDITY MEMBRANE LIPIDS SALINE SOLUTION, HYPERTONIC STEROLS FATTY ACIDS GLYCEROPHOSPHATES PHOSPHOLIPIDS SACCHAROMYCES CEREVISIAE |