About This Project

Cyanobacteria are photosynthetic bacteria that convert CO₂ into oxygen using light. They are abundant in our oceans and account for a large part of the oxygen on earth. With higher productivity rates than plants, cyanobacteria are emerging as a potential low-cost biobased alternative to chemical carbon capture. We aim to create genetically engineered cyanobacteria that fix higher CO₂ than the natural strains. This will contribute to a scalable, low-energy approach to decarbonise the atmosphere.

Ask the Scientists

What is the context of this research?

The latest Intergovernmental Panel for Climate Change report states that to avoid increasing global warming by more than 2°C, we need to capture or reduce emissions by 17 billion tons per year. Currently, we emit 39 billion tons of CO₂ annually, and only 0.1% are captured. The problem is that available decarbonisation technologies are too energy intensive. Removing 17 billion tons of CO₂/year with the leading CCS technology would require more than twice the energy produced in the world today. Fast-growing cyanobacteria could offer an alternative route to mass-scale decarbonisation. By using directed evolution (DE), we aim to produce strains that have an increased capacity for carbon sequestration directly from the air, whilst growing in nitrogen-enriched wastewater effluents.

What is the significance of this project?

This project endeavours to alleviate two key bottlenecks to scaling bio-based CCUS: carbon fixation rate and nutrient sourcing. At present, microalgae cultivation relies on supplementation with tonnes of nitrates, phosphates and other fertilisers. Cyanobacteria have the potential to assimilate these ions from enriched wastewater such as agricultural run-off and water treatment effluents. Therefore, a strain that can tolerate wastewater and maintain high productivity would be able to significantly reduce the cost of sourcing chemical additives to provide nitrogen. By applying DE on the naturally fast growing cyanobacteria strain PCC 11901, we aim to select for an improved net CO₂ fixation rate and also a robust tolerance to consuming nutrients from wastewater directly.

What are the goals of the project?

We will use DE, a method in which natural strains are randomly mutated and selected artificially for their useful attributes. We will apply DE to two genes in PCC 11901: ccaA, which regulates the carbon influx, and ndhR, a regulator of carbon fixation genes. We aim to create variants of these genes that will potentially lead to an increase in CO₂ fixation. With this strategy we would generate desired traits through iterative rounds of genetic diversification and library screening and selection. We will test the selected strains both in lab media and wastewater, since the value of using cyanobacteria for CCS relies on cheap and sustainable nitrogen sources. A strain with enhanced carbon fixation that can thrive in wastewater would be a silver bullet for mass scale CCS.