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Medwed C, Holzinger A, Hofer S, Hartmann A, Michalik D, Glaser K, Karsten U. Ecophysiological, morphological, and biochemical traits of free-living Diplosphaera chodatii (Trebouxiophyceae) reveal adaptation to harsh environmental conditions. Protoplasma 2021; 258:1187-1199. [PMID: 33550447 PMCID: PMC8523416 DOI: 10.1007/s00709-021-01620-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/28/2021] [Indexed: 05/14/2023]
Abstract
Single-celled green algae within the Trebouxiophyceae (Chlorophyta) are typical components of terrestrial habitats, which often exhibit harsh environmental conditions for these microorganisms. This study provides a detailed overview of the ecophysiological, biochemical, and ultrastructural traits of an alga living on tree bark. The alga was isolated from a cypress tree in the Botanical Garden of Innsbruck (Austria) and identified by morphology and molecular phylogeny as Diplosphaera chodatii. Transmission electron microscopy after high-pressure freezing (HPF) showed an excellent preservation of the ultrastructure. The cell wall was bilayered with a smooth inner layer and an outer layer of polysaccharides with a fuzzy hair-like appearance that could possibly act as cell-cell adhesion mechanism and hence as a structural precursor supporting biofilm formation together with the mucilage observed occasionally. The photosynthetic-irradiance curves of D. chodatii indicated low light requirements without photoinhibition at high photon flux densities (1580 μmol photons m-2 s-1) supported by growth rate measurements. D. chodatii showed a high desiccation tolerance, as 85% of its initial value was recovered after controlled desiccation at a relative humidity of ~10%. The alga contained the low molecular weight carbohydrates sucrose and sorbitol, which probably act as protective compounds against desiccation. In addition, a new but chemically not elucidated mycosporine-like amino acid was detected with a molecular mass of 332 g mol-1 and an absorption maximum of 324 nm. The presented data provide various traits which contribute to a better understanding of the adaptive mechanisms of D. chodatii to terrestrial habitats.
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Affiliation(s)
- Cynthia Medwed
- Institute of Biological Science, Applied Ecology & Phycology, University of Rostock, Albert-Einstein-Strasse 3, D-18059, Rostock, Germany
| | - Andreas Holzinger
- Department of Botany, Functional Plant Biology, University of Innsbruck, Sternwartestrasse 15, A-6020, Innsbruck, Austria
| | - Stefanie Hofer
- Department of Pharmacognosy, University of Innsbruck, Innrain 80-82, A-6020, Innsbruck, Austria
| | - Anja Hartmann
- Department of Pharmacognosy, University of Innsbruck, Innrain 80-82, A-6020, Innsbruck, Austria
| | - Dirk Michalik
- Institute of Chemistry, University of Rostock, Albert-Einstein-Strasse 3a, D-18059, Rostock, Germany
- Leibniz Institute of Catalysis, Albert-Einstein-Strasse 29a, D-18059, Rostock, Germany
| | - Karin Glaser
- Institute of Biological Science, Applied Ecology & Phycology, University of Rostock, Albert-Einstein-Strasse 3, D-18059, Rostock, Germany
| | - Ulf Karsten
- Institute of Biological Science, Applied Ecology & Phycology, University of Rostock, Albert-Einstein-Strasse 3, D-18059, Rostock, Germany.
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