Methodological approaches for unraveling ill-natured moments of generally good-natured Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae is a two-sided coin; it has a beneficial, biotechnological value with a strong connotation of reliable safety, but also a negative, potentially pathogenic nature on the other hand. This review is discussing the methodological approaches that were used for unraveling putative virulence traits that should separate pathogenic and non-pathogenic strains. These methods can be sorted in four main groups regarding physiology/morphology, genetics, proteomics and host-pathogen interactions. They can be used to enrich the knowledge regarding e.g. invasive growth, rapid molecular identification, cell-wall adhesions and virulence of yeast pathogens, respectively. Most of these methods have been adapted mainly to the leading yeast pathogen Candida albicans or bacterial pathogens. S. cerevisiae, on the other hand, can act as a weak opportunistic pathogen in certain conditions and its pathogenicity is not comparable to the pathogenicity of C. albicans, therefore it is welcomed that new, modified methods are introduced. New approaches already showed a strong induction of invasive growth under nutrient starvation and at temperatures typical for human fever (37-39°C), revealing the potential of S. cerevisiae strains to cause a disease in humans. A repressive effect on the other hand was observed in the presence of salts, anoxia and some preservatives, which implies the importance of food safety measures. The role of cell-wall proteins, which are involved in the adhesion to plastic material like catheters and other cell wall components that bind to the epithelial surface in the host, should be subjected to more detailed studies. The mechanisms for antimycotic resistance and rapid molecular identification techniques that would identify potentially pathogenic strains should be the focus of research, as well.