National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Induction of extracelullar phosphatases in acidotolerant planktonic algae from the genus Coccomyxa: impact of phosphorus concentration and form
Macholdová, Markéta ; Nedbalová, Linda (advisor) ; Ševců, Alena (referee)
Phosphorus is frequently a limiting factor for phytoplankton in freshwater ecosystems, because algae and cyanobacteria are able to incorporate it only in a dissolved inorganic form. Phytoplankton evolved several mechanisms to overcome phosphorus limitation. One of them is the production of extracellular phosphatases. These enzymes are excreted on the surface of cells or released to the environment. They hydrolyze organic molecules containing phosphorus, which can be then incorporated by cells. This mechanism can influence the competitiveness of algae living in environments that are characterised by long-term phosphorus limitation (that is caused e.g. by the effect of low pH). In this study the influence of phosphorus concentration and form on extracellular phosphatase activity under laboratory conditions was investigated. The two experimental strains of the genus Coccomyxa (Chlorophyta) were isolated from acidified localities with different phosphorus availability  Plešné Lake and Hromnické Lake. Extracellular phosphatase activity on a single-cell level was measured using the FLEA technique and fluorescence microscopy. The FLEA technique allows direct visualization of phosphatases on the cell surface by incubating the samples with the artificial substrate ELF® 97 phosphate. Extracellular...
Acidophilous cyanobacteria and algae
Macholdová, Markéta ; Nedbalová, Linda (advisor) ; Medová, Hana (referee)
Due to natural processes and human activity extremely acidic habitats, whose pH does not exceed 3.0, are formed on Earth. These are especially areas affected by the acid mine drainage (AMD) and of volcanic activity. The biodiversity of these habitats is greatly reduced, but there are microorganisms that are very well adapted to such extreme conditions. These organisms are termed as acidophilic. Cyanobacteria and algae are the only primary producers at extremely acidic sites and thus play a crucial role in these ecosystems. Although they must overcome several problems that are associated with such an environment (excess of H+ ions, increased concentrations of heavy metals), they developed a range of ecophysiological adaptations and life strategies that allow them to inhabit it. These are mainly the ultrastructural changes in the cell membranes, special metabolic processes and the production of special substances and enzymes. Acidophilic species are present across almost all taxonomic groups of cyanobacteria and algae. Interest in acidophilic organisms has increased in recent decades due to their potential use in biotechnology. Knowledge of their taxonomy, ecology and ecophysiology can also be used in paleobiology and exobiology.

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