Ice nucleation activity in lichens.

摘要: A newly discovered form of biological ice nucleus associated with lichens is described. Ice nucleation spectra a variety from the southwestern United States were measured by drop-freezing method. Several epilithic lichen samples genera Rhizoplaca, Xanthoparmelia, and Xanthoria had nuclei active at temperatures as warm −2.3°C densities 2.3 × 106 to more than 1 108 g−1 −5°C (2 4 orders magnitude higher any plants infected nucleation-active bacteria). Most tested activity above −8°C. Lichen substrates (rocks, plants, soil) showed negligible bacteria not isolated lichens, was destroyed heat (70°C) or sonication, indicating that lichen-associated are nonbacterial in origin differ chemically previously described nuclei. An axenic culture fungus Rhizoplaca chrysoleuca detectable −1.9°C an density 4.5 −5°C. It hypothesized these which both frost tolerant dependent on atmospheric moisture, derive benefit increased moisture deposition result nucleation.