Extreme dehydration observed in Antarctic Turgidosculum complicatulum and in Prasiola crispa

Gaseous phase hydration effect of extremely dehydrated thallus of the Antarctic lichenized fungus Turgidosculum complicatulum and of green alga Prasiola crispa was observed using hydration kinetics, sorption isotherm, 1H-NMR spectroscopy and relaxometry. Three bound water fractions were distinguished: (1) very tightly bound water, (2) tightly bound water and (3) a loosely bound water fraction detected at higher levels of hydration. Sorption isotherm was sigmoidal in form and well fitted using Dent model. The relative mass of water saturating primary water binding sites was ΔM/m0 = 0.055 for T. complicatulum and ΔM/m0 = 0.131 for P. crispa. 1H-NMR free induction decays (FIDs) for T. complicatulum and for P. crispa were superpositions of a solid signal component, and one averaged liquid signal component for P. crispa thallus (\(T_{2L}^{*}\) ≈ 80 µs) or two liquid signal components coming from a tightly bound (\(T_{{2L_{1} }}^{*}\)≈ 71 µs) and from a loosely bound water fraction (\(T_{{2L_{2} }}^{*}\)≈ 278 µs) for T. complicatulum. 1H-NMR spectra recorded for T. complicatulum and for P. crispa thalli revealed one averaged mobile proton signal component L. The total liquid signal component expressed in units of solid (L1 + L2)/S suggests the presence of water soluble fraction in T. complicatulum thallus.