While most humans don’t have the means or tools to bear witness to them, many of the world’s smallest species have extraordinary survival mechanisms. Certain soil bacteria, for example, can consume hydrogen from the air and utilize it as fuel if they are starved of all other nutrients.
Mycobacterium smegmatis: Small but mighty
This microbial trick led Australian researchers from Monash University to discover and isolate an enzyme from Mycobacterium smegmatis that processes ingested hydrogen and outputs it as energy. This now has the potential to be used to power items like small devices and implants.
“We’ve known for some time that bacteria can use the trace hydrogen in the air as a source of energy to help them grow and survive, including in Antarctic soils, volcanic craters, and the deep ocean,” said Chris Greening, a microbiology professor at Monash and co-author of this study. “But we didn’t know how they did this, until now.”
What is “Huc”?
While hydrogen accounts for only 0.00005 percent of the atmosphere, this isolated hydrogen catalyzing enzyme, dubbed Huc by the researchers, can quickly devour it. While bacteria pull 70 million tonnes [77 million tons] of hydrogen from the atmosphere each year, the chemical structure of Huc allows the enzyme to split the hydrogen molecules to form an electron transport chain, thereby creating an electrical circuit in the cell.
“Huc is extraordinarily efficient,” says principal author Rhys Grinter of the Biomedicine Discovery Centre at the university. “Unlike all other known enzymes and chemical catalysts, it even consumes hydrogen below atmospheric levels – as little as 0.00005 percent of the air we breathe.”
The team spent five years hitting multiple dead ends before isolating Huc, but once they did, they were awed by several features of this tiny superpower. In addition to its resistance to oxygen (which poisons many hydrogen catalyzers), it provides incredibly adaptable and long-term storage and is similar to a battery that never runs out of power – as long as there is even a trace of hydrogen bouncing around in the air.
“It is astonishingly stable,” said Ashleigh Kropp, Ph.D. candidate and study co-author. “It is possible to freeze the enzyme or heat it to 80 °C [176 °F], and it retains its power to generate energy. This reflects that this enzyme helps bacteria to survive in the most extreme environments.”
Tapping into Huc’s impressive potential
However, it’s a little early to celebrate Huc’s impending commercial triumph. Thus far, scientists have only generated a little amount of charge from a small supply of the enzyme.
Still, it’s an amazing discovery for the researchers, which started out with the goal of simply learning more about how bacteria function in the environment. While its practical use suggests that the first step would be to utilize it as battery cells for small devices like clocks, LED globes, or rudimentary computers, Grinter believes that with time, financing, and dramatically increasing the enzyme’s density, powering a car is a potential outcome.