Most people think of mushrooms as something to eat—or steer clear of, depending on the variety. Now, researchers have turned a common edible mushroom into something quite different indeed—a way to generate electricity.
A team at Stevens Institute of Technology has taken a white-button mushroom that was bought at a grocery store and super-charged it using 3D-printed clusters of cyanobacteria swirls of graphene nanoribbons. The former generates electricity and the latter collects the current, said Manu Mannoor, an assistant professor of mechanical engineering at Stevens.
|Pictured is a white button mushroom equipped with 3D-printed graphene nanoribbons (black), which collects electricity generated by densely packed 3D-printed cyanobacteria (green). Researchers at the Stevens Institute of Technology in New York developed the method for modifying a common mushroom in this way. (Image source: Sudeep Joshi, Stevens Institute of Technology)|
The Bionic Mushroom
“In this case, our system—this bionic mushroom—produces electricity,” he said in a Stevens Institute news release. “By integrating cyanobacteria that can produce electricity, with nanoscale materials capable of collecting the current, we were able to better access the unique properties of both, augment them, and create an entirely new functional bionic system.”
Bioengineers have known for some time of cyanobacteria’s ability to produce electricity. However, these microbes don’t survive long on artificial, bio-compatible surfaces, which has limited their use in bio-engineering applications.
To solve this problem, Mannoor and Sudeep Joshi, a postdoctoral fellow in his lab, turned their attention to white-button mushrooms, they said. Because these mushrooms host a rich microbiota but not cyanobacteria specifically, the researchers wondered if they could provide the right environment—i.e., nutrients, moisture, pH, and temperature—required for cyanobacteria to produce electricity for a longer period.
In experiments, the team showed that cyanobacterial cells lasted several days longer when placed on the cap of a white button mushroom versus a silicone material and a dead mushroom used as controls.
“The mushrooms essentially serve as a suitable environmental substrate with advanced functionality of nourishing the energy producing cyanobacteria,” Joshi said. “We showed for the first time that a hybrid system can incorporate an artificial collaboration, or engineered symbiosis, between two different microbiological kingdoms.”
Researchers then used a robotic arm-based 3D printer to print electronic ink containing the graphene nanoribbons to serve as an electricity-collecting network atop the mushroom’s cap. Like needles sticking into a single cell to access electrical signals inside it, the network acts as a nano-probe to access bio-electrons generated inside the cyanobacterial cells, Mannoor said.
Another bio-ink containing cyanobacteria was then printed onto the mushroom’s cap in a spiral pattern, Mannoor said. This pattern intersects with the electronic ink at multiple contact points, where electrons could transfer through the outer membranes of the cyanobacteria to the conductive network of graphene nanoribbons. Shining a light on the mushrooms activated the cyanobacterial photosynthesis, generating a photocurrent.
Live Long and Prosper
Researchers demonstrated two key phenomena with their work: that cyanobacteria can live longer in a state of engineered symbiosis, and that the amount of electricity these bacteria produce can vary, depending on the density and alignment with which they are packed.
To the latter point, they showed that the more densely packed together they are, the more electricity they produce. Using 3D printing, researchers could assemble them so as to boost their electricity-producing activity eight-fold more than the casted cyanobacteria using a laboratory pipette, they said.
The research has a wider scope to help researchers better improve their understanding of cells' biological machinery, Mannoor noted. Scientists are hoping to use the intricate molecular composition of cells to fabricate new technologies and systems for defense, healthcare, and the environment, he said.
“With this work, we can imagine enormous opportunities for next-generation bio-hybrid applications. For example, some bacteria can glow, while others sense toxins or produce fuel. By seamlessly integrating these microbes with nanomaterials," Mannoor noted, "we could potentially realize many other amazing designer bio-hybrids for the environment, defense, healthcare, and many other fields.”
Elizabeth Montalbano is a freelance writer who has written about technology and culture for 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time, she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.
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