The dominant fluxes in the carbon cycle are innately biological. Photosynthesis removes inorganic carbon from the atmosphere and oceans, ultimately sequestering a small fraction in rocks, while respiration produces CO₂ from organic matter and constitutes a nearly equal counter flux. Microbes, in particular, are key catalysts in the carbon cycle, having invented oxygen-producing photosynthesis and being responsible for the overwhelming majority of global respiration today. Although we don’t have direct access to organisms from the past or future, our growing capacity to predictably manipulate microbial genomes enables us to build exemplary microbes to learn the environmental constraints on these key biological processes. Through examples from my research, I will show that “synthetic biology” tools can be used to reveal fundamental constraints on microbial photosynthesis and respiration, which, in turn, enrich our understanding of the history of Earth’s atmosphere. More broadly, I will argue that there is a tremendous opportunity to learn about our planet by using molecular biology tools and data to pursue Earth science questions.

About this Series: The Department Lecture Series at EAPS at MIT is a series of weekly talks given by leading thinkers in the areas of geology, geophysics, geobiology, geochemistry, atmospheric science, oceanography, climatology, and planetary science. For more information please contact Madelyn Musick: mmusick@mit.edu