Alternate sources of energy are essential to alleviate global problems of climate change, causing people to opt for solar energy, wind energy, and other sources. Researchers from Yale University discovered how some bacteria generate electric currents, which may potentially be a new source of energy in the future.
The new study involving the bacteria Geobacter sulfurreducens was published in the journal Nature Chemical Biology. The authors wrote that the multifunctional living materials, such as algae and bacteria, "are attractive due to their powerful ability to self-repair and replicate."
Geobacter, commonly found in soil, is one of the unique natural materials that have electronic functionality. As the bacteria consume organic waste, they produce electrons that generate small electric currents that make their way into underground minerals such as iron oxide. To do that, "Geobacter breathe through what is essentially a giant snorkel, hundreds of times their size," explained Professor Nikhil Malvakar from Yale University.
The natural snorkel is made of conductive filaments called nanowires, which allow the bacteria to breathe in oxygen-deprived environments or deeper parts of the soil where minerals are found. Billions of Geobacter are constantly generating electric currents and producing electricity on the seafloor.
Developing a New Source of Energy
These experiments could lead to developing organic batteries as a source of energy that is eco-friendly. Malvankar shared, "We believe this [discovery] could be used to make electronics out of the bacteria beneath your feet," since the lack of abundant minerals in a laboratory setting hinders the abundant growth of the species.
The team's former experiments demonstrated how an electric field stimulates the microbes within a small electrode. The microbes arranged themselves to create biofilms and breathed out electrons together.
"They stack up like high-rise apartments, hundreds of stories tall," Malvankar described. "And they can all share the same electric grid, constantly dumping electrons."
However, a major obstacle for scientists is figuring out how the bacteria at the top of a tall structure can move electrons to the base and nanowires. It would require the microbes to exhale electrons more than 1,000 times its size.
Unique Structure of Nanowires
Using microscopy methods, they searched for molecules that enable the bacteria to exhale electrons over long distances. What they wound were amino acids within the proteins of the nanowires, shared Sibel Ebru Yalcin, from the university's Microbial Sciences Institute.
The electrochemically active bacteria, or EAM, have a unique nanowire made of a protein called OmcZ. These proteins then form metallic nanowires. The researchers demonstrated how stimulating Geobacter biofilms with an electric field produces electricity up to 1,000 more efficiently than they do in the soil. The protein enables them to exhale electrons over long distances.
In conclusion, the authors wrote that if the bacteria and their unique features can be "biologically produced, highly conductive protein nanowires may help to guide the development of seamless, bidirectional interfaces between biological and electronic systems."
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