Low-temperature immobilization of water in Antarctic Turgidosculum complicatulum and in Prasiola crispa. Part I. Turgidosculum complicatulum
| Autor: | Maria Olech, P. Kijak, Monika Marzec, J. Fitas, M. Bacior, P. Nowak, H. Harańczyk |
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| Rok vydání: | 2019 |
| Předmět: |
Magnetic Resonance Spectroscopy
Proton Resolution (mass spectrometry) Diffusion Analytical chemistry Antarctic Regions 02 engineering and technology 01 natural sciences Spectral line DSC Colloid and Surface Chemistry Ascomycota Chlorophyta Freezing 0103 physical sciences Molecule Bound water freezing resistance Physical and Theoretical Chemistry lichens Calorimetry Differential Scanning 010304 chemical physics Chemistry Water Surfaces and Interfaces General Medicine 021001 nanoscience & nanotechnology NMR Thallus Cold Temperature phase growth Proton NMR Thermodynamics Water Microbiology 0210 nano-technology Biotechnology |
| Zdroj: | Colloids and Surfaces B: Biointerfaces. 173:869-875 |
| ISSN: | 0927-7765 |
| DOI: | 10.1016/j.colsurfb.2018.10.059 |
| Popis: | The studies of low-temperature immobilization of bound water in Antarctic lichenized fungus Turgidosculum complicatulum were performed using 1H NMR and DSC over a wide range of thallus hydration. 1H NMR free induction decays were decomposed into a solid component well described by the Gaussian function and two exponentially decaying components coming from a tightly bound water and from a loosely bound water fraction. 1H NMR spectra revealed one averaged mobile proton signal component. 1H NMR measurements recorded in time and in frequency domain suggest the non-cooperative bound water immobilization in T. complicatulum thallus. The threshold of the hydration level estimated by 1H NMR analysis at which the cooperative bound water freezing was detected was Δm/m0 ≈ 0.39, whereas for DSC analysis was equal to Δm/m0 = 0.375. Main ice melting estimated from DSC measurements for zero hydration level of the sample starts at tm = –(19.29 ± 1.19)°C. However, DSC melting peak shows a composed form being a superposition of the main narrow peak (presumably melting of mycobiont areas) and a broad low-temperature shoulder (presumably melting of isolated photobiont cells). DSC traces recorded after two-hour incubation of T. complicatulum thallus at –20 °C suggest much lower threshold level of hydration at which the ice formation occurs (Δm/m0 = 0.0842). Presumably it is a result of diffusion induced migration of separated water molecules to ice microcrystallites already present in thallus, but still beyond the calorimeter resolution. |
| Databáze: | OpenAIRE |
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