This contribution summarizes a piece of challenges that I had to deal with during the PhD at the Chair of Biotechnology, Microbiology and Food safety and represented a basis for further continuation of the research under the scope of postdoctoral project. The challenges were focused on the yeast Saccharomyces cerevisiae as a model for studying new emerging opportunistic yeast pathogens. Specifically, the solutions were searched in the physiology of invasive growth, in the expression of cell wall mannoproteins and in the identification power of DNA microsatellites. Due to weak methodology in that fields, new methodological solutions were searched in all mentioned areas.
B.03 Paper at an international scientific conferenceCOBISS.SI-ID: 4147576
This work was presented at the 13th International Congress on Yeasts (ICY) in USA (August 26-30) as a poster. It is an overview of research results obtained at the Chair of Biotechnology, Microbiology and Food Safety on Saccharomyces cerevisiae virulence traits, which were the basis for this postdoctoral project. In the past two decades S. cerevisiae was reported in increased incidence of systemic, invasive infections in immunocompromised adults and newborns. Regarding numerous biotechnological applications in which the species is successfully used for centuries, it can be hypothesized that the pathogenicity is the property of certain strains only. These strains arguably have specific virulence traits, like adhesiveness, invasiveness and the ability to grow at increased temperatures. The main interest in our studies was to establish a methodology for evaluating the virulence traits of S. cerevisiae clinical strains and to connect the traits to strain pathogenicity. Because of a serious lack of methodology in this area, we first developed a quantitative agar invasion assay and a procedure for quantitative profiling of cell wall proteins. The invasiveness of clinical strains were measured at various growth conditions (temperatures, pH values, nutrient starvation, modified atmosphere, and different concentrations of NaCl, CaCl2 and preservatives) to learn more about the triggers which are significant for developing invasive behavior in food or in human host. A significant increase in the invasion of the virulent strains was determined at temperatures typical for human fever (37–39 °C), revealing the potential to cause a disease in humans. A strong preference for invasive growth (meaning high relative invasion) was observed also on nitrogen- and glucose-depleted media. On the other hand, a strong repressive effect on invasion was found in the presence of salts, anoxia and some preservatives. Examination of call wall proteins revealed the presence of up to 20 cell wall protein bands with molecular masses in the range 60-220 kDa, for which significant changes in the protein profile expression, relevant to different cultivation temperature, cell morphology (invasive vs. noninvasive growth) and yeast strain, were observed. The results showed relatively high diversity in the examined putative virulent traits among S. cerevisiae strains, which opened further questions about the virulence potential of various strains used in food and food products.
B.06 OtherCOBISS.SI-ID: 4124536
This contribution was presented at the 13th International Congress on Yeasts (ICY) in USA (August 26-30) as a poster. It is presenting the quorum sensing or intercelullar communication, which was observed in yeast and is connected to virulence through the mechanisms, which are triggered by nutrient depletion. At the Chair of Biotechnology, Microbiology and Food Safety we developed a rapid and simple methodology for monitoring QS molecules, which enables the examination of the phenomenon in question.
B.06 OtherCOBISS.SI-ID: 4124280