Over the course of 2.5 billion years, cyanobacteria have evolved the capacity to efficiently absorb light in order to produce energy. To harvest that photosynthetic power, scientists have synthetically engineered a mutualistic relationship between microbes and a host mushroom in order to produce electricity.
This “environment-friendly and green source” takes a page straight out of nature’s book. In their natural habitat, bacterial colonies function together to accomplish complex tasks like bioluminescence and antibiotic production. Similarly, mushrooms thrive off each other in self-contained groups capable of communicating and sharing resources. So, why not combine the two?
Researchers created “bionic” mushrooms by 3D printing cyanobacteria contained in hydrogel (bio-ink) directly onto button mushroom caps in a spiral pattern. In “self-serving biophysiological conditions”, the mushroom provides shelter, moisture, and nutrients to the bacteria, which in turn produces energy through chlorophyll cells. The integration is mutually beneficial, giving it the new nickname "engineered symbiosis". To capture that energy, graphene nanoribbons – thin strips of superconductive material called “electronic ink" – were printed in a pattern that intersects with the bacteria, capturing electrons released through the outer membranes of the bacteria.
Shining a light on the bionic mushroom enabled the cyanobacteria to produce 65 nanoAmps through photosynthesis. In short, they were able to grow electricity.
Though this isn’t enough to power an electronic device, the researchers say a group of mushrooms could create enough current to light up an LED and shows the potential for future versions.
"Our designer bio-hybrid (Bionic Mushroom in our case) is a true example of a green bioelectricity generator as it is a three-dimensional seamless integration of cyanobacteria, mushroom (part of nature), and graphene nanoribbons," said study author Sudeep Joshi in an interview with IFLScience, continuing that although the team has successfully demonstrated a working method toward clean and green energy, there is still a long road ahead in competing with fossil fuels.
“Micro-organisms that possess such photosynthetic capabilities embrace potential applications toward advancements in fields such as bacteriology, energy harvesting, genetic engineering, and bacterial nanobionics,” wrote the authors in Nano Letters.
The team says they are working on ways to generate higher currents across complex arrangements of bacterial species and perhaps expanding to use other varieties of "useful" bacteria that exhibit unique properties such as bioluminescence and virulence.
"These bacterial species can be utilized to engineer a bio-hybrid system showcasing the particular property that the selected bacteria exhibits. We believe that our approach of bacterial nanobionics can pave the way forward for many novel 'designer bionic hybrids,'" explained Joshi.