Mycobacterium smegmatis. Kredit: Vader1941 / Wikimedia Commons. CC BY-SA 4.0
Recently, there has been a big media and professional hit on Australian scientists with an “enzyme that makes electricity out of thin air.” Somewhat clickbait media shorthand aside, it’s definitely fascinating stuff. They found an enzyme that uses even an extremely small amount of hydrogen gas in the air and produces electricity from it.
Rhys Grinter on the right. Credit: Monash University.
We have known for some time that many bacteria can use trace amounts of atmospheric hydrogen as an energy source in nutrient-poor environments. Thanks to this, they survive in polar soils, volcanic craters and similar extreme habitats. But until now it was not clear how they actually do it.
Microbiologist Rhys Grinter of Monash University and his colleagues isolated the enzyme responsible for this energy masterpiece from a common soil actinomycete Mycobacterium smegmatis. It is a hitherto unknown enzyme from the group of NiFe hydrogenases, named Huc hydrogenase. As Grinter enthuses, Huc is miraculously effective. Concentrations of hydrogen in the atmosphere are extremely low. This is because we breathe air in which there is only about 0.00005 percent of molecular hydrogen.
logo. Credit: Monash University.
The researchers examined Huc hydrogenase using cryo-electron microscopy (cryo-EM) and determined its internal structure. Using electrochemistry, they observed how this enzyme generates electricity at minute concentrations of hydrogen in the air. Laboratory analyzes have shown that Huc is also exceptionally stable. The enzyme can be frozen or heated to 80°C and still be able to generate electricity. The Huc shows that it is a tool for survival in extreme conditions.
In short, Huc hydrogenase is a natural battery that produces a stable electric current thanks to the hydrogen in the surrounding air. Research into this enzyme is in its infancy, but there is already considerable potential for the development of small electronic devices powered by “air,” for example as alternatives to solar-powered devices.
At the same time, it can be assumed that similar enzymes are common in bacteria. Protein engineers who can tune the already remarkable properties of Huc will certainly come in handy. Here, it seems, is a bacterial source of clean energy that we can count on for energy considerations for decades to come.
Video: Australian scientists discover how to turn air into electricity
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