The world is facing a global energy crisis as CO2 levels in the atmosphere continue to increase at an alarming rate. What if CO2 could be converted into energy-rich products that sustainably benefit people and protect the planet? 

Enter bacteria.

            Society has a complicated relationship with bacteria. It is acknowledged for aiding digestion and helping produce food such as yogurt. Equally, bacteria cause alarm for its destructiveness as the culprit for diseases. From the soil that humans step on to inside the human gut, these single-celled organisms live and thrive in a diverse range of environments. My research is centered on the belief that bacteria can be the energy producers of the future that can both save and fuel the planet.

            Like humans, bacteria have a complex metabolism and can perform a variety of reactions to generate energy for their survival. Similar to the way humans process different foods, bacteria can process different substrates and convert them into energy-rich products. Acetogenic bacteria can process CO2 as a substrate.

Bacteria are highly capable of adapting to their environment because they can produce their own enzymes. They are essentially their own enzyme factory. An enzyme is a biological molecule that significantly increases the rate of a chemical reaction. Each type of enzyme is a specialist; optimized to perform exactly one reaction at the highest level with incredible efficiency.

CO2 conversion is difficult to achieve because it is thermodynamically very stable and kinetically inert. This makes the conversion of the linear molecule extremely challenging. However, enzymes appear to perform this reaction effortlessly. They are a true masterpiece of nature: incredibly fascinating, but just as complex.

The first aim of the project is to study enzymes as a catalyst in Solar-Driven Biohybrid Systems for COconversion. In these systems, the enzyme is wired to light absorbing nanoparticles. When light shines on the particles, the energy is transferred to the enzymes which can then perform CO2 conversion.

In my studies, the enzyme is isolated from the bacterium via a purification process. This allows me to study the catalytic machinery in great detail. However, the major limitation of enzymes is that they are fragile. Enzymes have a limited lifetime when they are isolated because they lack the protection mechanisms of the bacterium. Therefore, the second aim of my project is to use the whole bacteria instead of the isolated enzymes as biocatalysts in the Solar-Driven Biohybrid Systems for COconversion.

Melanie Miller

NanoDTC Associate, c2018