Single cell analysis reveals unexpected growth phenotype of S. cerevisiae

Abstract

Single cell analysis is mainly limited to single time-point measurements, without the possibility to track behavioral changes of a single cell or its descendents. Here, the integration of a spatiotemporal single cell lab-on-a-chip system with an automated cultivation device allows single cell analysis under defined growth conditions and, especially, semiautomated cell retrieval and growth kinetic analysis of the single cell descendants. Performance of the new platform was evaluated using the yeast Saccharomyces cerevisiae. The yeast was singularized in the lab-on-a-chip (Envirostat), which combines the possibility of cell cultivation with cell analysis. Singularized cells were collected in a microtiter plate and cultivated in a semiautomated cultivation device (Bioscreen C). S. cerevisiae showed highly reproducible and glucose concentration independent growth kinetics in population experiments. Yet, growth kinetics in cultures inoculated with only one or few cells exhibited strong variations, because of an unexpected growth phenotype: colony formation in submerse cultures. Interestingly, the colony-like structures grew for more then 60 h and were stable for at least 82 h, despite rigorous shaking. Cell agglomeration due to pseudohyphal growth could be excluded, suggesting changes in cell wall properties of yeast populations starting from a single yeast. Single cell analysis still exhibits unexpected obstacles. Nevertheless, this new single cell analysis platform can be used for studying cellular dynamics of single cells and expanded cell populations thereof.