title: Distribution of scytonemin in endolithic microbial communities from halite crusts in the hyperarid zone of the Atacama Desert, Chile.
abstract: Scytonemin, a UV-screening molecule produced by certain Cyanobacteria to protect against harmful UV radiation, was studied in endolithic cyanobacterial colonies in the halite crust from one of the driest places on Earth - the hyperarid zone of the Atacama Desert. The distribution of the pigment within the evaporitic crust was studied in detail by various independent analytical methods: Raman spectroscopy (including Raman imaging); advanced microscopic observations (fluorescence microscopy, confocal laser scanning microscopy, low-temperature scanning electron microscopy); and spectrophotometric analyses. The differences in scytonemin biosynthesis were mapped within the colonized interior layers, which can be divided into scytonemin-rich and scytonemin-poor zones. A 532 nm laser for excitation proved to be an ideal excitation source with which to observe the relative content of scytonemin within a particular cell aggregate, as well as between different cell aggregates; based on the scytonemin/carotenoid Raman signal intensity ratio of selected corroborative bands for these two compounds. Significantly, scytonemin was found to accumulate within a decayed biomass in the surface portions of the halite crust. These were found to be highly enriched in both the absolute scytonemin content (as documented by UV/VIS spectrophotometry) and its content relative to other pigments associated with the cyanobacterial cells (e.g. carotenoids and chlorophyll).
authors: Institute of Geochemistry, Mineralogy and Mineral Resources, Charles University in Prague, Prague 2, Czech Republic.
authors: Petr
authors: P
authors: Vítek
authors: Jan
authors: J
authors: Jehlička
authors: Carmen
authors: C
authors: Ascaso
authors: Vlastimil
authors: V
authors: Mašek
authors: Benito
authors: B
authors: Gómez-Silva
authors: Héctor
authors: H
authors: Olivares
authors: Jacek
authors: J
authors: Wierzchos
mesh_terms: D002338:Carotenoids / Q000378:metabolism; D002677:Chile; D002734:Chlorophyll / Q000378:metabolism; D000458:Cyanobacteria / Q000378:metabolism*; D003889:Desert Climate; D019015:Geologic Sediments / Q000382:microbiology*; D007211:Indoles / Q000378:metabolism*; D008027:Light; D010636:Phenols / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D007211:Indoles; D010636:Phenols; D002734:Chlorophyll; C083368:scytonemin; D002338:Carotenoids
keywords: Chroococcidiopsis; adaptation strategy; halophile; salt