Effect of selenium on the cellular structure and oxidative response of the yeasts Saccharomyces cerevisiae and...

Selenium is an element with diverse biological effects that, at higher concentrations, can cause oxidative stress and cell damage. Therefore, it is essential to understand its impact on yeast cells, which can serve as a model for studying selenium toxicity.

This study aimed to evaluate the effect of selenium on the physiology, cellular structure, and oxidative response of the yeasts Saccharomyces cerevisiae ATCC 7090 and Rhodotorula glutinis CCY 20-2-26. Changes in cellular structure, reactive oxygen species (ROS) levels, and ultrastructural alterations were examined under the influence of varying selenium concentrations.

Yeast cells were cultured in various selenium concentrations. The analysis included spectroscopic methods, flow cytometry, electron microscopy (TEM, SEM), and analysis of the surface chemical composition of yeast biomass (XPS). ROS and peroxide levels, as well as changes in cell structure, were also assessed.

The yeast Saccharomyces cerevisiae demonstrated the ability to adapt its cellular structure to the presence of selenium, resulting in an increase in the proportion of C-C and C-H bonds to 53.5 % (at a concentration of 10 mg Se⁴⁺/L). Superoxide production increased by 26.14 % at a concentration of 10 mg Se⁴⁺/L, while ROS levels remained low (0.21 %). In Rhodotorula glutinis, however, over 50.71 % of cells were in a state of early apoptosis at a concentration of 20 mg Se⁴⁺/L, and the integrity of cellular structures was severely compromised. XPS analysis revealed the presence of Se-S bonds, suggesting the involvement of detoxification mechanisms involving selenium binding to the thiol groups of proteins and peptides, forming less toxic selenium-sulfur complexes.

This study demonstrated that the yeast S. cerevisiae exhibits a greater ability to adapt to selenium stress than R. glutinis. Selenium detoxification mechanisms, exemplified by the formation of selenium-sulfur complexes, play a crucial role in the response to oxidative stress. These results could serve as a starting point for further research on the effects of selenium on yeast cells.