The history of life on Earth is intimately intertwined with the history of oxygen in the atmosphere. While Earth’s atmosphere has been oxygenated for billions of years, a varied set of challenges has stood in the way of life making use of this oxygen for metabolic energy, especially in the context of multicellular groups which are widely considered to be oxygen-limited. During the Proterozoic, oxygen was too low for multicellular communities to drive the metabolism of their interior cells. After the Neoproterozoic oxygenation event, however, abundant oxygen existed but diffusional limitations prevented its use deep inside multicellular groups. Multiple strategies appear to have been employed allowing multicellular communities and organisms to exist during these periods – specifically, phototrophy during the Proterozoic, and facilitated oxygen diffusion by oxygen binding proteins during the Phanerozoic.

Using synthetic biology techniques, we have imported both of these mechanisms into the “snowflake yeast” model system to investigate how they affect the ecology and evolution of multicellular groups. By engineering yeast to contain both of these molecular innovations, we are exploring how they affect the physiology of multicellular groups and affect course of long-term evolution experiments and the physiology of aerobic respiration and energy metabolism in oxygen-limited environments.