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Simulated soil crust conditions in a chamber system provide new insights on cyanobacterial acclimation to desiccation
Author(s) -
Raanan Hagai,
Oren Nadav,
Treves Haim,
Berkowicz Simon M.,
Hagemann Martin,
Pade Nadin,
Keren Nir,
Kaplan Aaron
Publication year - 2016
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12998
Subject(s) - desiccation , photosynthesis , acclimatization , biology , cyanobacteria , dew , dehydration , dew point , irradiance , chlorophyll fluorescence , botany , ecology , physics , quantum mechanics , meteorology , bacteria , condensation , thermodynamics , biochemistry , genetics
Summary Environmental research often faces two major hurdles: (i) fluctuating spatial and temporal conditions and consequently large variability in the organisms' abundance and performance, and (ii) complex, costly logistics involved in field experiments. Measurements of physiological parameters or molecular analyses often represent single shot experiments. To study desiccation acclimation of filamentous cyanobacteria, the founders and main primary producers in desert biological soil crusts ( BSC ), we constructed an environmental chamber that can reproducibly and accurately simulate ambient conditions and measure microorganism performance. We show that recovery from desiccation of BSC cyanobacteria and L eptolyngbya ohadii isolated thereof are strongly affected by dehydration rate following morning dew. This effect is most pronounced in cells exposed to high light and temperature in the dry phase. Simultaneous measurements of water content, gas exchange and fluorescence were performed during dehydration. Photosynthetic performance measured by fluorescence begins declining when light intensity reaches values above 100 μmol photons m −2 s −1 , even in fully hydrated cells. In contrast, photosynthetic rates measured using O 2 evolution and CO 2 uptake increased during rising irradiance to the point where the water content declined below ∼ 50%. Thus, fluorescence cannot serve as a reliable measure of photosynthesis in desert cyanobacteria. The effects of drying on gas exchange are discussed.