Creating Fertilizer Out of Thin Air: Sounds Weird, But Researchers Can Do It

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Think of plants creating their fertilizer. The need to spread fertilizer on the plants will be gone, and food production will increase. It might seem impossible, but researchers at the Washington University in St. Louis found that they can make it sound less like a sci-fi novel and turn it into reality.

The research was published in mBio, and it was led by Himadri Pakrasi, the Glassberg-Greensfelder Distinguished University Professor (Department of Biology in Arts & Sciences) and also the director of the International Center for Energy, Environment and Sustainability (InCEES); and Maitrayee Bhattacharyya-Pakrasi who is a senior research associate in biology.

Using Nitrogen from the Atmosphere

To create fertilizer, it takes a lot of energy, and it produces greenhouse gases in the process, sometimes being inefficient. The fertilizer is used to deliver nitrogen to plants so that they can create chlorophyll for photosynthesis. However, the commercial fertilizer provides less than 40% of the nitrogen it contains to the plant because it is washed away by rain, ending up in rivers, lakes, etc. Here comes another problem: the fertilizer feeds algae which grow too much, and they block sunlight for plants and animals in the water.

Trying to find a solution, researchers found a different source of nitrogen. The atmosphere of our planet has almost 78% nitrogen, and Himadri Pakrasi with his team have just engineered a bacterium which can use the gas from the atmosphere (it can “fix” nitrogen).

Plants cannot fix nitrogen from the air, but a bacterium named cyanobacteria can photosynthesize like plants and use the nitrogen from the air, even when the oxygen interferes with the process.

This Bacterium Has a Circadian Rhythm

In their research, Pakrasi said they used a bacterium named Cyanothece because of this weird thing:

“Cyanobacteria are the only bacteria that have a circadian rhythm.”

That meant that Cyanothece is active during the day and converts sunlight to use it as a fuel, while at night it fixes nitrogen.

But the team had to continue their research: they wanted to transfer the genes from Cyanothece to a different type of cyanobacteria: Synechocystis, to make this bacterium fix nitrogen from the air, too. Pakrasi explains that they had to discover the right genes in the bacterium that were connected to the circadian rhythm:

“We saw a contiguous set of 35 genes that were doing things only at night and they were basically silent during the day.”

The team removed the oxygen from Synechocystis, adding the genes from the Cyanothece. But at that point, Synechocystis could only fix 2% of nitrogen compared to Cyanothece. Removing some of the genes (and keeping only 24 from the Cyanothece), the Synechocystis could fix nitrogen 30% more than the Cyanothece.

Seeing the positive results, Pakrasi said:

“This means that the engineering plan is feasible. I must say, this achievement was beyond my expectation.”

The next step is to collaborate with scientists and see if their discovery can be applied to creating nitrogen-fixing plants. Bhattacharyya-Pakrasi concludes that if they can make plants use the nitrogen in the air, “it will be a significant change in agriculture.”

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Andre Blair s is the lead editor for Advocator.ca. He holds a B.A. in Psychology from the University of Toronto, and a Master of Science in Public Health (M.S.P.H.) from the School of Public Health, Department of Health Administration, at the University of North Carolina at Chapel Hill. Andre specializes in environmental health, but writes on a variety of issues.


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