Privileged planet: nitrous oxide breathers found (Introduction)

by David Turell , Friday, June 21, 2024, 21:30 (156 days ago) @ David Turell

Are very important:

https://phys.org/news/2024-06-bacteria-greenhouse-gases-previously-thought.html

"Caltech researchers have discovered a new class of enzymes that enable a myriad of bacteria to "breathe" nitrate when in low-oxygen conditions. While this is an evolutionary advantage for bacterial survival, the process produces the greenhouse gas nitrous oxide (N2O) as a byproduct, the third-most potent greenhouse gas, after carbon dioxide and methane.

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"Most cells in the biosphere utilize certain proteins called reductases to breathe, or respire, oxygen, but Murali and her team discovered a wide swath of reductases that had evolved closely related proteins to respire nitric oxide, producing nitrous oxide in the process.

"Nitric oxide and nitrous oxide are intermediate chemicals produced during denitrification, the process by which bacteria break down nitrate, the chemical found in fertilizers. Bacteria are able to switch from respiring oxygen to nitric oxide in many different environments—wetlands, alpine soils, lakes, and so on—when oxygen levels start to drop below approximately 10% of atmospheric levels.

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'Geobiologists had previously believed that anaerobic pathways like nitrate respiration evolutionarily came before the ability to breathe oxygen, in our early single-celled ancestors. This study "flips the script," according to Fischer, demonstrating that the proteins that enable nitrate respiration actually evolved from those that respire oxygen, two billion years ago.

"'Microbiologists often predict what metabolisms microbes are capable of performing based on comparative genomics," explains co-author James Hemp, a former Caltech postdoctoral scholar now of the company Meliora.bio in Utah.

"'However, these hypotheses are rarely tested experimentally. Our work has dramatically increased the biochemical diversity of one of the most studied enzyme families in microbiology. This should serve as a warning that automated metabolic analysis without experimental verification can lead to incorrect conclusions of the functions of microbes and communities.'"

Comment: the biochemical processes creating our atmosphere ae shown to be much more complex. This is added to our knowledge, showing all the interlocking layers that are beneficial.