Bacteria can use air to fix nitrogen, study reports

Avatar By Joseph Scalise | 2 years ago

Researchers from Washington University in St. Louis have found evidence that it may be possible to engineer plants that can create their own fertilizer, a discovery that could drastically impact global agriculture.

While fertilizer is a key part of growing crops, making the substance is quite energy intensive and the dirt generates greenhouse gases that drive climate change. In addition, as it only delivers 40 percent of its nitrogen to the plant, it is also incredibly inefficient.

The team behind the new study hopes to fix that by taking nitrogen from another source: the Earth’s atmosphere. 

To do that, the researchers engineered a bacterium to fix the nitrogen in the air. That is significant because it is the first step towards getting plants to do the same thing.

While no plant on Earth can naturally fix the nitrogen in the atmosphere, there is a type of photosynthetic bacteria — known as Cyanothece — that can. 

In the study, the team analyzed those organisms and found that they, like humans, go through a circadian rhythm. They photosynthesize during the day and then fix nitrogen at night.  

That process sparked the scientists to take genes from the bacteria and put them into another type of cyanobacteria known as Synechocystis.

They first located the gene sequence behind the day-night cycle and transferred it over. That then caused Synechocystis to fix nitrogen at 2 percent of Cyanothece. However, when the team removed some of the genes, Synechocystis was able to fix nitrogen at a rate of more than 30 percent of Cyanothece.

Though fixation rates dropped when the team added oxygen to the process, they went back up with the addition of more Cyanothece genes.

In that way, the team managed to give the bacteria the ability to fix nitrogen on their own.

“This means that the engineering plan is feasible,” said study co-author Maitrayee Bhattacharyya-Pakrasia, a researcher at the University of Washington in St. Louis, according to Science Daily. “I must say, this achievement was beyond my expectation.”

Now that researchers have proof that it is possible to transfer nitrogen fixing, they next plan to dive deeper into the process to create nitrogen-fixing plants. That could then create much more efficient crops and help the 800 million subsistence farmers around the world.

“If it’s a success,” added Bhattacharyya-Pakrasi, according to Phys.org.  “it will be a significant change in agriculture.”

The study is published in the journal mBio.