With Designer Bacteria, Crops Could One Day Fertilize Themselves (2017)

For the last 100 years, ever since German chemists Fritz Haber and Carl Bosch figured out how to pluck fertilizer out of thin air with brute-force chemistry, farmers have relied on an imperfect product to make their plants grow: fertilizer. Production of the stuff burns through 3 percent of the world’s natural gas annually, releases tons of carbon into the atmosphere, and runs off into rivers and streams and aquifers. Relying on fossil fuels to grow food was never exactly sustainable. But as the world thinks about what it will take to feed 9 billion people in a rapidly changing climate, it’s become unconscionable.

One solution would be for everyone to start eating a lot more legumes.

Peanuts, peas, and many types of beans are climate-friendly because they basically make their own fertilizer. They play host to a special class of microbes called nitrogen fixers that invade the root hairs of their host plants, forming knobby nodes and converting free nitrogen in the soil to ammonia. That's the stuff plants need to make food for themselves via photosynthesis.

Most of the world’s biggest food crops—corn, wheat, rice—aren’t so hospitable to nitrogen-fixers. Which is why they require so much artificial fertilizer to grow.

Or, you could engineer a host of microbes that have all the nitrogen-fixing power of the peanut’s follicular friends, but with the ability to colonize the roots of any plant. Then you could paint that bacteria onto shelf-stable seeds and ship them anywhere in the world.  That’s what a new startup, boasting the largest seed investment of any ag tech company so far this year, plans to do. On Thursday, German biochem giant Bayer announced it was joining forces with Ginkgo Bioworks, a Boston-based synthetic biology shop, to create a new venture to wean the world off fertilizers.

“We fundamentally know that microbes will provide benefits to plants that chemicals cannot,” says Mike Miille, head of biologics for Bayer Crop Science, who will also be the new company’s interim CEO. “But these nitrogen-fixing microbes have been limited in what they can do by which plants' evolution has pushed them toward. We’re trying to change that.” The company (which is so far unnamed) will operate jointly out of Ginkgo’s soon-to-be-completed automated DNA foundry and Bayer Crop Science’s R&D center in West Sacramento. Bayer’s science team has already started screening its microbial library for candidate critters to ship to Boston. With hundreds of thousands of bacteria to sift through, they hope to pull together a diverse set of nitrogen-fixers for scientists at Ginkgo to begin sequencing as early as next month.

This prospecting phase could give them a good idea which genes are most important for nitrogen-fixing. (Though, without a rich set of soil microbe reference genomes, this is going to be a serious fishing expedition.) But if it works, they plan to use that genetic roadmap to design and synthesize custom DNA for new microbes they can grow and study in the lab.

Ultimately, this group is trying to design a bacteria that combines nitrogen-fixing skills with seed coat strengths—it’s got to be able to survive without water for long periods of time and then activate as soon as it gets wet. It also has to like growing in a petri dish (most wild nitrogen-fixers don't). Oh, and it’s got to stand up to industrial production and formulation processes, too.

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