A comparative analysis of gaseous phase hydration properties of two lichenized fungi: Niebla tigrina (Follman) Rundel & Bowler from Atacama Desert and Umbilicaria antarctica Frey & I. M. Lamb from Robert Island, Southern Shetlands Archipelago, maritime Antarctica

Resumen:
Gaseous phase hydration properties for thalli of Niebla tigrina from Atacama Desert, and for Umbilicaria antarctica from Isla Robert, maritime Antarctica, were analyzed using H-1-NMR relaxometry, spectroscopy, and sorption isotherm analysis. The molecular dynamics of residual water was monitored to distinguish the sequential binding very tightly, tightly, and loosely bound water fractions. These two species differ in hydration kinetics faster for Desert N. tigrina [A(1) = 0.51(4); t(1) = 0.51(5) h, t(2) = 15.0(1.9) h; total 0.7 for p/p(0) = 100%], compared to Antarctic U. antarctica [A(1) = 0.082(6), t(1) = 2.4(2) h, t(2) = [26.9(2.7)] h, total 0.6 for p/p(0) = 100%] from humid polar area. The H-1-NMR measurements distinguish signal from tightly bound water, and two signals from loosely bound water, with different chemical shifts higher for U. antarctica than for N. tigrina. Both lichen species contain different amounts of water-soluble solid fraction. For U. antarctica, the saturation concentration of water soluble solid fraction, c(s) = 0.55(9), and the dissolution effect is detected at least up to Delta m/m(0) = 0.7, whereas for N. tigrina with the similar saturation concentration, c(s) = 053(4), this fraction is detected up to the threshold hydration level equal to Delta M/m(0) = 0.3 only.

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