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USATÎI, Agafia; EFREMOVA, Nadejda; CHISELIŢA, Natalia; BEŞLIU, Alina; BATÎR, Ludmila; DADU, Constantin; TĂNASE, Ana. Estimation of cell viability at the contact of yeasts with ZnO and Fe3O4 nanoparticles. In: Microbial Biotechnology. Ediția 4, 11-12 octombrie 2018, Chișinău. Chișinău, Republica Moldova: Institutul de Microbiologie şi Biotehnologie, 2018, p. 156. ISBN 978-9975-3178-8-7.
Ediția 4, 2018
Conferința "Microbial Biotechnology" |
Chișinău, Moldova, 11-12 octombrie 2018
Cell viability tests carried out by the determination of colony-forming unit (CFU) are increasingly used to determine the toxicity of different types of chemical compounds, nanocomposites or biomaterials. In microbial biotechnology, for functional tests of the degree of inhibition or stimulation of a compound observed in dose - response reaction, it is proposed to use the terms “half maximal effective concentration” (EC50) or “half maximal inhibitory concentration” (IC50) of the compound. These parameters provide an opportunity to conduct a comprehensive study of nanoparticle toxicity. The present research has been focused on estimating the effects of ZnO nanoparticles with dimension <100 nm and Fe3O4 with dimension of 10 and 30 nm on cell viability of two yeast strains of the genus Saccharomyces and Rhodosporidium . Analyzing the results obtained at 24 hours of contact of Saccharomyces cerevisiae CNMNY- 20 strain with ZnO (<100 nm) nanoparticles, it was found that the viability rate practically did not change. For concentrations of 0.5-15 mg/L, the viability rate was between 96-87.5% compared to control. Rhodosporidium toruloides CNMN-Y-30 strain samples demonstrated modifications in cell viability under the influence of ZnO (<100 nm) nanoparticles in concentrations of 1-30 mg/L. Relevant results were observed at yeast contact with ZnO nanoparticles in concentrations of 20-30 mg/L, when the percentage of viable cells decreased to 59%. The obtained results can be summarized as follows: ZnO (<100 nm) nanoparticles in concentrations from 0.5 mg/L to 30 mg/L added to YPD culture medium induced some variations of the viability of yeasts Saccharomyces cerevisiae CNMN-Y-20 and Rhodosporidium toruloides CNMN-Y-30. For nanoparticles concentrations used in our experiments, the half maximal effective concentration (EC50) and half maximal inhibitory concentration (IC50) have not been recorded. Exploratory data analysis of the action of Fe3O4 nanoparticles with dimensions of 10 and 30 nm showed that the rate of viability varied depending on their size and concentration. The determination of colony-forming units (CFU) for Rhodosporidium toruloides CNMN-Y-30 strain at 24 hours of contact with 10 nm Fe3O4 nanoparticles in concentrations of 0.5-30 mg/L has revealed a high sensitivity of yeast to the action of iron oxide nanoparticles. The toxic effects were evident at concentrations of 20, 25 and 30 mg/L, when viability decreased to 40-32% compared to control. Low viability values were noted in the experiments where yeast cells were in contact with 30 nm Fe3O4 nanoparticles. Concentrations of 25-30 mg/L reduced cell viability to 75-60% compared to control. Thus, half maximal inhibitory concentration (IC50) was specific for Fe3O4 nanoparticles of 10 nm at 20 mg/L concentration. Thus, the test for yeast viability by determining colony forming units (UFC) is highly reliable, but, in some cases, the interpretation of the results may be inaccurate due to errors in serial dilutions or inoculation of biological material on Petri dishes. In this context, other procedures of nanoparticles toxicity evaluation, such as determination of oxygen consumption, impact on cell membrane integrity, antioxidant activity are also recommended.