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Salt-induced changes in lipid composition and membrane fluidity of halophilic yeast-like melanized fungi

Martina Turk1, Laurence Méjanelle, Marjeta Sentjurc

  • 1Institute of Biochemistry, Medical Faculty, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia.

Extremophiles : Life Under Extreme Conditions
|April 6, 2004
PubMed

Insights

Melanized fungi like Hortaea werneckii adapt to salt by altering membrane lipids. Their membranes remain fluid and sterol-poor, crucial for survival in saline environments.

Area of Science:

  • Microbiology
  • Biochemistry
  • Environmental Science

Background:

  • Halophilic and halotolerant fungi inhabit saline environments like salterns.
  • Melanized yeasts, including Hortaea werneckii, Phaeotheca triangularis, and Aureobasidium pullulans, are adapted to high salt concentrations.
  • Understanding their membrane lipid adaptations is key to their survival strategies.

Purpose of the Study:

  • To investigate the impact of varying NaCl concentrations on the membrane lipid composition and fluidity of selected melanized fungi.
  • To compare the lipid profiles and membrane properties of halophilic and halotolerant fungi with salt-sensitive yeast.

Main Methods:

  • Cultivation of fungi (H. werneckii, P. triangularis, A. pullulans) at different NaCl concentrations.
  • Analysis of fungal membrane sterol and phospholipid composition.
  • Gas chromatography to determine fatty acid profiles.
  • Electron paramagnetic resonance (EPR) spectroscopy to assess membrane fluidity.

Main Results:

  • Ergosterol was the predominant sterol; total sterol content remained stable under salt stress.
  • Phosphatidylcholine and phosphatidylethanolamine were major phospholipids; C16 and C18 fatty acids, especially C18:2Delta9,12, were abundant.
  • Salt stress increased fatty acid unsaturation in H. werneckii and A. pullulans, but decreased it in P. triangularis.
  • Halophilic fungi exhibited lower sterol-to-phospholipid ratios and more fluid membranes compared to salt-sensitive yeast.

Conclusions:

  • Melanized fungi maintain membrane fluidity through specific lipid compositions, including lower sterol content and altered fatty acid unsaturation.
  • These adaptations are crucial for survival and function in high-salinity environments.
  • Membrane fluidity is a key factor in the halotolerance of these yeast-like fungi.

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