About This Project

Studying mechanisms of CO2 uptake from extreme environments and their potential use in microalgae based carbon capture

Ask the Scientists

What is the context of this research?

Despite high rates of carbon fixation, microalgae, specifically cyanobacteria, are not widely used as a tool for capture of industrial CO2 emissions. CO2 normally reacts with water to form bicarbonate, which cyanobacteria actively transport bicarbonate by exchanging it with sodium ions; this transport is the largest energy cost of microalgal carbon concentration (1). In conditions with high concentrations of CO2 instead of bicarbonate, cyanobacteria rely on electrons from the light driven splitting of water to convert CO2 into bicarbonate. This process competes with carbon fixation into sugars for electrons derived from water splitting. . Cyanobacteria reach high densities that prevent light from penetrating the medium resulting in “dead zones” with low photosynthetic activity

What is the significance of this project?

Uncoupling CO2 uptake from light availability can have significant impacts on the ability of microalgae to capture CO2 from industrial sources, and in turn the economics of biological CO2 capture. Light dependence limits the accumulation of biomass from photoautrophs to about 3g/L compared to 30-100g/L for heterotrophic bacteria (2)

Carbon fixing microbes in extreme environments, such as hydrothermal vents, couple carbonic anhydrase activity to proton pumping rather than electron transfer. Enzyme engineering can increase the catalytic activity of these enzymes involved in light independent CO2 uptake, reducing the costs associated with industrial scale cultivation of microalgae, while increasing biomass production.

What are the goals of the project?

The goals of this project are to characterize the catalytic rates of enzymes involved in extremophilic CO2 uptake and conversion using computational models. This data, and other simulations from known carbonic anhydrase enzymes with exceptional rates of activity will be used to guide enzyme engineering efforts. The end goal of this project is an protein that enables microalgae to efficiently uncouple CO2 uptake from light availability