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Euglena gracilis as a promising eukaryotic model system for fast detection of high pressure induced cell destruction

Stoltze, Julia, Izydor, Marika, Hainthaler, Markus, Richter, Peter, Schlücker, Eberhard, Lebert, Michael
Environmental and experimental botany 2017 v.133 pp. 50-57
Euglena gracilis, ambient temperature, chemistry, enzymes, ethidium, eukaryotic cells, flagellum, food industry, high pressure treatment, median effective concentration, models, pharmaceutical industry, photosystem II, pressure, staining, swimming
High hydrostatic pressure (HHP) is a promising method for the inactivation of cells and enzymes in many applications (e.g. food industry, pharmaceutical industry, chemistry). The effects of various high-hydrostatic pressures (20MPa, 50MPa, 55MPa, 60MPa, 75MPa, 100MPa, 150MPa, 200MPa, 400MPa) on the unicellular flagellate Euglena gracilis were determined: (a) life/dead staining with ethidium bromide (EtBr), (b) loss of flagellum, (c) movement behavior, (d) recovery after 7d, (e) photosystem II quantum yield (Y(PSII)). Pressure was applied for 300s at room temperature (pressure increment and decrement: 10MPas−1). The EC50 value of vitality (EtBr-positive cells) directly after pressure application was 109MPa. Cell vitality was not impaired below 100MPa. No recovery of cells after 7d-cultivation in fresh medium was observed after pressure treatment above 100MPa. Flagellum-based free swimming of cells was already impaired at pressures above 50MPa, where some cells started metabolic movement behavior. From 75MPa to 100MPa all cells moved metabolically, while at higher-pressure all cells became immotile. In the pressure range between 75MPa and 200MPa, cells lost their flagellum. Interestingly, cells pressurized with 400MPa retained their flagella. Directly after HHP-treatment EC50 of Y(PSII)-inhibition was about 101MPa, after 6h about 102MPa. The use of fluorescence-based methods is considerably fast, easy and reliable. Because of the different easily recordable parameters, we believe that Euglena gracilis is a promising test organism to determine HHP-effects on eukaryotes. The effects on photosynthesis indicate impacts on intracellular membrane and protein complexes.