Microbes are the hidden heroes of our Earth, populating the dirt, the oceans, our skin, and more. Some microbes specialize in breaking things down, like the bacteria that cause food to decay over time. Others specialize in building- creating the fundamental building blocks of life. A special class of these are capable of taking nothing more than atmospheric gases and sunlight (in a process known as photosynthesis) and creating sugars, fats, and proteins. Typically, these microbes are consumed by larger organisms so that the nutrients can support the growth of more complex systems. If they are not consumed the small photosynthesizers will pass on and sediment in their environment, forming a new layer over the Earth’s surfaces.

One such photosynthetic microbe- cyanobacteria- is known to be particularly efficient at capturing carbon dioxide from the atmosphere and converting it into building blocks.  These macromolecules are not only useful as nutrients, but in our modern day may be employed as fuels, pharmaceutical molecules, etc. Amazingly, it is also now known that electricity can be extracted directly from the internal processes of these organisms, making them effective solar-to-electricity conversion systems.

To capture electricity from the microorganisms, they need to be placed in proximity to a material suited to receive it. Such a system, which pairs microorganisms with a tailored (inorganic) material, is referred to as “biohybrid”. Biohybrid energy-conversion systems are well-known, however, the mechanism of their function and sources of inefficiency remain poorly understood. Throughout my work, I am exploring the cellular environment in functioning biohybrids using operando fluorescence confocal microscopy. I will additionally be seeking to better understand the biological mechanisms of energy export by constructing minimal artificial cells to compare to existing microorganisms.

Graphical abstract: example images showing live cells being imaged with fluorescent dyes within a biohybrid set-up (left) and artificial cell mimics during synthesis (right)

Leanne Milburn

NanoDTC Associate, a2022