GREEN CYANO: Developing a cyanobacterial technology for making industrial chemicals from CO2

Reducing CO2 emissions and preventing further warming of the earth is the greatest challenge of our time.

To rapidly mitigate climate change and achieve the global ambition for greenhouse gas emissions reduction, the inflow of further fossil carbon from the ground into our system must be reduced as quickly as possible and by high volumes.

This PhD provides the student an opportunity to make a meaningful impact to society by developing a sustainable cyanobacteria-based, low carbon-footprint route to a large volume chemical for Proctor & Gamble, the industrial partner.

Cyanobacteria have long been recognised as solar-powered cell factories suitable for production of precursors of valuable industrial chemicals.

Ability to grow rapidly on recycled water without the need for prime agricultural land, fertilisers and freshwater makes cyanobacteria a sustainable resource for industrial exploitation.

Structural and physiological adaptations for running photosynthesis more efficiently underpin the superior conversion efficiency of solar energy-to-biomass in cyanobacteria.

However, a key challenge hindering production of high levels of target products is the failure to significantly divert metabolic flux towards engineered pathway(s) while maintaining growth. This makes commercial exploitation of cyanobacteria as green factories highly unfeasible. This project explores use of a three-stage strategy to redirect metabolites towards an engineered pathway.

Stage one is application of chemical stress to reconfigure cell metabolism, redistributing metabolic building blocks between normal metabolism and synthesis of stress-induced macromolecules. The photosynthetic machinery plays a central role in this stress-adaptive response.

While application of stress would normally limit biomass growth and/or activate cell death, stage two entails addition of novel extracellular biofilm-associated signals to block cell death and boost growth. The molecular mechanism by which the signals work will be investigated.

Stage three uses genetic manipulation to switch metabolic flux away from stress-induced macromolecules towards the engineered pathway and the valuable chemicals.

Finally, a scalable method for product extraction without use of organic solvents will be developed to make the entire workflow sustainable (Figure 1).