Balance of nature: bacteria fix nitrogen in oceans (Introduction)

by David Turell , Thursday, February 27, 2025, 19:20 (7 days ago) @ David Turell

Finding how the enzyme historically worked:

https://bigthink.com/life/the-lab-resurrecting-ancient-proteins-to-unlock-lifes-secrets...

"Yet for all its importance, nitrogen plays really hard to get. It makes up 78% of the atmosphere, but most living organisms can’t use it because it exists as inert nitrogen gas (N₂), held together by one of chemistry’s strongest glues: a triple bond. Breaking it requires immense energy — lightning can do it, but biologically, only one enzyme can: nitrogenase.

"Nitrogenase is found in nitrogen-fixing bacteria, named for their ability to break nitrogen’s triple bond and convert N₂ into ammonia (NH₃), a form life can use. In other words, these bacteria “fix” nitrogen into a usable form. Without this process, life as we know it wouldn’t exist.

"Kaçar and her team are particularly interested in nitrogenase because of its longevity and resilience. “At least seven or eight different enzymes can fix carbon from the atmosphere,” she explains. “For nitrogen, there’s only nitrogenase, and it evolved around 2.7 billion years ago. That kind of longevity suggests there’s something important about how life solved this problem early on.”

***

"one key event Kaçar is interested in is the Great Oxygenation Event, a period of time around 2.1 to 2.5 billion years ago when Earth’s atmospheric and oceanic oxygen levels increased dramatically. It was a time of massive environmental upheaval — many organisms died, ocean chemistry shifted dramatically, and life had to adapt to an entirely new atmosphere.

"But nitrogenase made it through.

“'We know nitrogen-fixing bacteria survived this event, but we don’t know whether nitrogenase changed along the way,” Kaçar says. “Did it subtly evolve to function in a different environment, or did life just work around it? That’s what we’re trying to find out.”

***

"Some plants already form symbiotic relationships with nitrogen-fixing bacteria, which produce nitrogenase. Legumes, like pea plants, host these bacteria in their roots, and in exchange, the bacteria convert atmospheric nitrogen into a form the plants can use, freeing them from relying on nitrogen already present in the soil. But many other plants, including major crops like corn and rice, don’t form these relationships.

"For years, researchers have explored ways to introduce nitrogen-fixing bacteria into crops to reduce reliance on synthetic fertilizers. This work is ongoing, but there is another problem: The environment is changing, and perhaps today’s nitrogenase isn’t the optimal solution for tomorrow’s world. Kaçar’s work may offer a new path forward.

***

“'We are partnering with botanists and chemical engineers to see if we can recreate nitrogenases from ancient Earth environments and introduce them into nitrogen-fixing bacteria. The goal is to pair these microbes with crops so they can be more resilient to climate change while relying less on synthetic fertilizers.”

"If successful, this research could offer a double benefit: a more sustainable way to fertilize crops while helping agriculture adapt to a rapidly changing climate. By looking billions of years into the past, Kaçar’s work could help solve one of the most pressing challenges of the future."

Comment: obviously very important research. Nitrogen is as important as carbon in the biochemistry of life.