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Genetically modified bacteria may be the key to plants that fertilize themselves

For decades, ever-increasing population growth has made people worried about the long-term sustainability of our planet. Perhaps the biggest concern? How best to feed everyone. Looking for a solution to this problem, scientists from Washington University in St. Louis have been searching for a means by which plants can create their own fertilizer. Such a breakthrough could mean that farmers would no longer have to buy and manually spread it on their crops in order for them to grow.

Their innovative solution involves a genetically engineered bacteria that is able to pull fertilizer out of thin air. Because bioavailable nitrogen is a critical nutrient for crop productivity, this could turn out to be an agricultural game-changer.

“A long-term and sustainable solution will be the plants fixing their own nitrogen,” Himadri Pakrasi, a professor in the department of biology in arts and sciences, told Digital Trends. “The energy required can come from the sun via photosynthesis. However, biological nitrogen fixation in bacteria is catalyzed by nitrogenase, an enzyme that is poisoned by oxygen, the product of photosynthesis. The exciting news from our study is that we have been able to engineer functional nitrogenase in cyanobacteria that perform photosynthesis and also produce oxygen. This is an important step toward engineering nitrogen-fixing crops in the future.”

For their study, the researchers were able to isolate genes in a cyanobacteria called cyanothece, which carries out photosynthesis during the day and uses nitrogen to create chlorophyll for photosynthesis during the night, and then splice them into another type of cyanobacteria. As a result, this new type of cyanobacteria was also able to pull nitrogen from the air. While the work is still at a relatively early stage, they are hopeful that the end result will be to apply these findings to create nitrogen-fixing plants.

“Engineering nitrogen-fixing plants is a grand challenge in agriculture, and it will take some time to achieve this dream,” Pakrasi said. “In collaboration with other plant scientists, we will next attempt to emulate our cyanobacterial engineering approach in vascular plants.”

A paper describing the work, “Engineering Nitrogen Fixation Activity in an Oxygenic Phototroph,” was recently published in the journal mBio.

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