About This Project

Engineering synthetic lichens to capture CO2

Ask the Scientists

What is the context of this research?

Photosynthetic organisms fix gigatons of atmospheric CO2 every day. They can also self replicate without human input, making them seem like the ideal scalable tool. However, a large fraction of this fixed carbon is released back into the atmosphere due to respiration. Additionally, achieving scales that would have a significant impact on climate change often necessitates costly bioreactors and ponds, or competition with food systems and the few remaining pristine ecosystems for land. Thus, designing photosynthetic organisms to fight climate change will require solving two major challenges: 1) Engineering mechanisms to slow the release of fixed carbon, and 2) Enabling zero-input growth that doesn’t compete with existing land-use.

What is the significance of this project?

Most efforts to increase the lifetime of photosynthetically fixed carbon have focused on strategies that channel it into compounds that have been shown to break down slowly, such as suberin. Unfortunately, this approach will create a selective pressure for the proliferation of microbes that can digest them, limiting its long-term efficacy. A promising alternative is to trap organic carbon in soil is association with minerals which prevent access by microbes. However, a successful biological CO2 removal strategy must also overcome the volatility of input costs and shifting land-use priorities. This will require designing organisms that can grow efficiently in barren lands without inputs.

What are the goals of the project?

The goal of this project is to develop a biological mechanism that catalyzes mineralization of photosynthetically fixed carbon to enable prolonged resilience to breakdown. For such a mechanism to be significantly impactful we hypothesize it would need to enable mineralization of a significant portion of the fixed carbon (>30%) and be stable when exposed to environmental fluctuations and microbes (half-life> 100 years). Another goal of this work is to install this mechanism in a photosynthetic organism capable of growing efficiently (growth rates similar to cover crops or industrial microbes) with zero-inputs on barren lands with minimal endemic life that are unusable for agriculture, such as rocky plains revealed by retreating glaciers.