Genome complexity: bacteria make elecricity from air (Introduction)

by David Turell , Thursday, March 09, 2023, 16:10 (415 days ago) @ David Turell

Using available hydrogen:

https://www.sciencealert.com/soil-bacteria-discovery-could-allow-us-to-produce-electric...

"It may sound surprising, but when times are tough and there is no other food available, some soil bacteria can consume traces of hydrogen in the air as an energy source.

"In fact, bacteria remove a staggering 70 million tonnes of hydrogen yearly from the atmosphere, a process that literally shapes the composition of the air we breathe.

"'We have isolated an enzyme that enables some bacteria to consume hydrogen and extract energy from it, and found it can produce an electric current directly when exposed to even minute amounts of hydrogen.

***

"Prompted by this discovery, we analyzed the genetic code of a soil bacterium called Mycobacterium smegmatis, which consumes hydrogen from air.

"Written into these genes is the blueprint for producing the molecular machine responsible for consuming hydrogen and converting it into energy for the bacterium. This machine is an enzyme called a "hydrogenase", and we named it Huc for short.

"Hydrogen is the simplest molecule, made of two positively charged protons held together by a bond formed by two negatively charged electrons. Huc breaks this bond, the protons part ways, and the electrons are released.

"In the bacteria, these free electrons then flow into a complex circuit called the "electron transport chain", and are harnessed to provide the cell with energy.

***

"Hydrogen represents only 0.00005 percent of the atmosphere. Consuming this gas at these low concentrations is a formidable challenge, which no known catalyst can achieve. Furthermore, oxygen, which is abundant in the atmosphere, poisons the activity of most hydrogen-consuming catalysts.

***

"With Huc isolated, we set about studying it in earnest, to discover what exactly the enzyme is capable of. How can it turn the hydrogen in the air into a sustainable source of electricity?

"Remarkably, we found that even when isolated from the bacteria, Huc can consume hydrogen at concentrations far lower even than the tiny traces in the air. In fact, Huc still consumed whiffs of hydrogen too faint to be detected by our gas chromatograph, a highly sensitive instrument we use to measure gas concentrations.

"We also found Huc is entirely uninhibited by oxygen, a property not seen in other hydrogen-consuming catalysts.

***

"""In short, this research shows how a fundamental discovery about how bacteria in soils feed themselves can lead to a reimagining of the chemistry of life."

Comment: this is how extremophiles can survive using enzymes of this sort.