Resource utilization and competition among yeasts

Abstract

One of the postulates of evolutionary theory is competition for limited resources. Previous studies show that there is a trade-off between yield and rate in resource utilization and ATP production pathways, implying that different metabolic strategies will result in different competition outcomes. Two main metabolic strategies used by micro-organisms are respiration and fermentation. Respiration maximizes the efficiency of ATP production, resulting in increased yields at the expense of the rate. In contrast, fermentation is an inefficient ATP production strategy, but it runs at a higher rate. Our goal was to study competition between fermentation and respiration and find conditions, such as resource availability, population and spatial structure, that favor dominance of those strategies. We used </>Saccharomyces cerevisiae and </>Kluyveromyces lactis tagges with different fluorescent protein as models for fermentation and respiration, respectively. We experimentally determined physiological parameters and used them in dynamic models of competition for resources in spatially homogeneous (well-mixed) and in spatially structured populations. The results show competition dynamics in different conditions and we discuss implications of those results in the evolution of metabolic strategies.