Atomic force microscopy study of yeast cells influenced by high voltage electrical discharge

Human cells are the eukaryotic ones. Simulation of wide-spectrum electromagnetic radiation influence on eukaryotic cells was performed with yeast which is usually used now in molecular biological and medical biological investigations as the ideal model of eukaryotic system. The aim of the research was to observe possible induced alterations of the cell morphology. Atomic force microscopy (AFM) and electron scanning microscopy (ESM) have been applied to image the surface of cells exposed to electromagnetic radiation. Electromagnetic radiation was provided in a reactor tank due to high-voltage electrical discharge in water (HVD) [1]. The total accumulated discharge energy (E) density per cell solution volume was varied. AFM images were obtained for the free cells placed on a polycrystalline corundum (polycor) substrate. Ten specimens fields contained around 100 cells each were explored. HVD applied to the cells altered their surface morphology. Particularly, the surface became corrugated at E<50 J/ml. However higher levels of energy (>50 J/ml) could destroy part of the cells. Microbiological experiments evidenced that yeast cells survived after treatment showed higher rate of the proliferation in the fresh nutrient medium comparing it with control cells which were not subjected to HVD treatment. Besides that new population of yeast which was received in our experiments using as the inoculum cells survived after HVD treatment were more resistant to another stress - dehydration-rehydration. The reached results demonstrate that HVD could be applied to enhance proliferation rate of the culture as well as for the obtaining of more resistant population.