Saccharomyces cerevisiae recovery from various mild abiotic stresses: Viability, fitness, and high resolution three-dimensional morphology imaging

Abstract

Environmental conditions have a huge impact on the development of all living things but are especially important in the case of single-celled organisms such as Saccharomyces cerevisiae that must respond quickly and appropriately to any change. Many molecular mechanisms of response to stress have been identified in yeast, but only a few reports address physiological and morphological changes. To investigate S. cerevisiae recovery from ten mild stress conditions and to describe the viability and fitness, we performed a series of growth analysis experiments. Moreover, label-free live cell imaging of yeast subjected to ten environmental stresses has been achieved using holotomography - a leading-edge high resolution 3D quantitative phase imaging. We determined that recovery times of yeast cultures subjected to hyperosmotic and sugar starvation stresses were the shortest, as were the doubling times. Substantially lower proliferation capacity was recorded in yeast after applying sugar- and AA starvation, and high pH stresses, compared to control. Furthermore, the stationary growth was much shorter after subjecting yeast to hypoosmotic and heat stresses, and much longer after anaerobic and UV stresses. Further, we determined changes in shape, colony formation, cell wall damage, volume, sphericity, protein and lipid contents in yeast cells under stress conditions. The most prominent changes were observed for UV and hyperosmotic stresses. Condluding, stress conditions applied to yest cultures affected them differently, causing detrimental effects to their growth, metabolism, fitness and morphology. Moreover, we have proven that holotomography is excellent for precisely determining morphological changes of single cells.