The development of photosynthesis in primitive cyanobacteria is recognised as one of the pivotal developments in the evolution of complex life on Earth.
However, photosynthesis itself – the conversion of sunlight into sugar – is a relatively inefficient process.
Now, researchers from the University of California, Berkeley (UCB), have uncovered a method that combines both approaches. Effectively, they have induced bacteria to coat themselves in tiny, highly efficient solar panels.
Lead researcher Kelsey Sakimoto worked with common bacteria known as Moorella thermoacetica. The species does not naturally photosynthesise, but Sakimoto and his colleagues induced a population of the microbes to cover themselves in semiconductor nanocrystals.
The work is an extension of research carried out by Peidong Yang, also at UCB, who specialises in creating inorganic semi-conductors and binding them to bacteria, producing useful chemicals from the interaction of carbon dioxide and water.
“The thrust of research in my lab is to essentially ‘supercharge’ nonphotosynthetic bacteria by providing them energy in the form of electrons from inorganic semiconductors, like cadmium sulfide, that are efficient light absorbers,” explains Yang.
Sakimoto chose M. thermoacetica as a research target because it produces acetic acid as a function of its normal respiratory cycle. The acid is currently the focus of widespread experimentation because of its usefulness in the creation of polymers and other commercial useful products, often achieved by the application of other bacterial species.
The researchers successfully induced the bacteria to bond with a combination of cadmium and the amino acid cysteine. Cysteine contains a sulfur atom, causing the bacteria to synthesise cadmium sulfide (CdS) nanoparticles – which function as solar panels.
The resulting hybrids – dubbed M. thermoacetica-CdS – produced acetic acid using carbon dioxide, water and light at a stunning 80% efficiency.
“Rather than rely on inefficient chlorophyll to harvest sunlight, I’ve taught bacteria how to grow and cover their bodies with tiny semiconductor nanocrystals,” says Sakimoto.
“These nanocrystals are much more efficient than chlorophyll and can be grown at a fraction of the cost of manufactured solar panels.”
The research was presented at the 254th National Meeting & Exposition of the American Chemical Society, held in Washington DC, US.
Andrew Masterson is a former editor of Cosmos.
Read science facts, not fiction...
There’s never been a more important time to explain the facts, cherish evidence-based knowledge and to showcase the latest scientific, technological and engineering breakthroughs. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science. Financial contributions, however big or small, help us provide access to trusted science information at a time when the world needs it most. Please support us by making a donation or purchasing a subscription today.