When it comes to the fuel sources of the future, we’re all familiar with solar energy, wind power, and even biofuels produced from corn or algae. But a team of scientists have recently discovered an even more quirky energy source, inspired by Mother Nature herself: mushrooms.

Not just any old mushroom, mind. Coined ‘bionic mushrooms’, what started out as a simple button mushroom from a grocery store now hosts a surface coating of cyanobacteria and veins of nanoscale graphene.

Cyanobacteria have been receiving increased attention from the scientific community as pressures mount to find alternative fuel sources, since these microorganisms are capable of producing small amounts of electrical energy from light. When exposed to light, cyanobacteria photosynthesise, and the small amount of electricity produced during this process is known as a photocurrent.

So why do we need the mushroom? Well, cyanobacteria aren’t known to survive for any length of time on artificial surfaces, and the living cap of the fungus offers prime growing conditions for the bacteria.

Mushrooms already host their own array of microbiota, so adding cyanobacteria to the mix isn’t a huge stretch of the imagination. They’re the perfect host, with the optimal temperature, surface nutrients and moisture content ready to keep the cyanobacteria living for much longer.

First, an electronic ink is used to embed graphene into the mushroom surface, as a means to collect the electrical current generated. Next, 3D printing is used to draw a spiral pattern of bio-ink, containing the cyanobacteria, across the mushroom cap. Finally, light is shone on the mushroom and the cyanobacteria get to work generating an electrical current.

The button mushroom with graphene stripes embedded and a swirl of cyanobacteria living on the cap. Photo Credit: Sudeep Joshi, Stevens Institute of Technology

The button mushroom with graphene stripes embedded and a swirl of cyanobacteria living on the cap.
Photo Credit: Sudeep Joshi, Stevens Institute of Technology

 

The researchers at the Stevens Institute of Technology in the US, whose findings were published in the journal Nano Letters, have called this process ‘engineered symbiosis’. They’re referring to mimicking the symbiotic relationships found in nature, whereby two organisms co-exist in a way that mutually benefits both parties. Classic examples include clownfish and sea anemones — or you and your gut microbiome.

The next step is for the researchers to up-scale this power output. At the moment, a single mushroom can’t produce enough energy to power a lamp, let alone charge your phone or light up your house. A group of bionic mushrooms wired up together, however, could produce enough of these ‘biocurrents’ to power a small LED light.

One avenue to explore is the use of genetically-modified cyanobacteria, which are able to photosynthesise at a higher rate and generate much stronger electrical currents. The study is part of a broader trend aiming to understand how biomechanical pathways and mechanisms can be ‘hijacked’ to help us produce materials or, in this case, energy.

The researchers believe that the potential for energy generation from creating bio-hybrids like this could be huge. These experiments have opened up discussions for next-generation bio-hybrids which aim to use the fungi-bacteria symbiosis in other areas than generating electrical current. Different types of bacteria are capable of producing biofuels, sense the presence of toxins, or even have the ability to glow. Apply the same method of using a living fungus as a bionic base and there’s scope for vast expansion of several industries, including biofuel and healthcare.

And, if all goes well, one day we could be thanking the humble button mushroom for helping to pave the way for a major source of green energy.

references

Joshi, S., Cook, E., & Mannoor, M. S. (2018). Bacterial Nanobionics via 3D Printing. Nano letters18(12), 7448-7456.

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