Switch Bioworks—a startup engineering nitrogen fixing microbes that colonize plant roots before switching on ammonia production several weeks into the growing season—has entered a strategic collaboration with Bayer Crop Science.
Bayer, which has spent a lot of time working with microbes engineered to produce fertilizer via a joint venture with Ginkgo Bioworks (Joyn Bio), says it can complement Switch Bio’s expertise with its “capabilities in product development, formulation, field testing and commercialization, as well as our understanding of crop genetics. That’s the only way we’re going to accelerate progress.”
Switch Bio founder and CEO Tim Schnabel, PhD told AgFunderNews: “Initially the collaboration will bring together Switch’s best strains with a variety of Bayer’s leading hybrids. While I cannot comment on Joyn’s strategy, what Switch brings to table has the potential to be value-add to traits already developed by Joyn.
“Biological nitrogen fixation has been somewhat of a holy grail, and solving it may need a systems approach including strain stacking and trait stacking.”
He added: “Partnering with Bayer is a testament to the potential of our platform, and this collaboration marks a pivotal milestone for our company.”
‘Switchable strains out-colonize always-on strains’
While several players have engineered microbes to produce nitrogen fertilizer, they can struggle to establish on plant roots, while those that establish reliably often don’t produce enough ammonia to create real value for growers, claims California-based Switch Bio.
Switch engineers its microbes to first compete with the native soil microbiome and establish themselves on plant roots before a genetic switch turns on that triggers ammonia production.
In grow-room studies, this produced five times more nitrogen than “always-on” control strains and has recently been tested in field trials on corn across the Midwest. Switch has also secured approvals for field release in Brazil from the National Technical Biosafety Commission, said Schnabel.
“Our work at Switch has shown that switching between growth and nitrogen production results in increased nitrogen fixation on plants because switchable strains out-colonize always-on strains.”
The firm has not disclosed the precise environmental trigger but noted that it responds to a change in the soil environment after several weeks and does not require any intervention on the part of farmers.
Switch Bio deploys a mixture of nitrogen-fixing soil microbes that produce an enzyme called nitrogenase that enables them to combine nitrogen with hydrogen to produce ammonia, helping growers reduce synthetic fertilizer use.
Unlike approaches based primarily on selecting mutants that have spontaneously evolved to produce ammonia, meanwhile, Switch “has gone in and actually built this thing from the bottom up,” said Schnabel. “And that’s the reason that the regulatory approval for these field trials [from USDA and the EPA] is such a big deal because the level of complexity of the engineering is first in class.
“It’s truly a bioengineering new-in-class type of biofertilizer microbe that we’re putting in the field.”
Field trials
In field trials, Switch has been trying to answer three key questions, said Schnabel:
- Can the microbes establish and persist on corn roots?
- Does the genetic switch activate at the right time?
- Which microbes should form the eventual product?
The company has been measuring the composition of the wider root microbial community, the relative abundance of its engineered strains, switch activation—detectable through a DNA-sequence change—plant nitrogen-response indicators and yield.
According to Schnabel: “Although harvest is still over a month out, we’re seeing some exciting early signals walking the plots and when it comes to drone data looking at leaf nitrogen. We’ve also been able to show that the switches turn on in the field.
“That being said, these trials are for late stage product development, principally studying colonization and switching across many strains and conditions. They are not statistically powered enough to expect fertilizer replacement or yield in the first year.”
Regulatory and commercial outlook
For Switch, which is targeting commercialization within two to three years, the ultimate ambition is not to eliminate synthetic nitrogen entirely, said Schnabel. Replacing 25% of nitrogen fertilizer while maintaining yields would constitute a major win, with biology’s likely upper limit around 50%, he added.
The business case—which is coming into sharper focus given the pressure the war on Iran has put on the fertilizer market—is based principally on supplying nitrogen at a lower cost with a relatively small dose of microbes applied in-furrow, he said.
“We have a techno-economic analysis that’s sitting behind this, but you can calculate exactly how many microbes you have to make per acre, and the cost of producing them is much less than the cost of producing 40 or 80 pounds of chemical nitrogen fertilizer.
“Farmers have paper thin margins, so even just $20 to $30 in savings per acre on fertilizer would be a huge deal.”
Further reading:
Switch Bioworks tests ‘switchable’ nitrogen-fixing microbes in corn for fertilizer
Can microbes supply half a crop’s nitrogen? Pivot Bio thinks so
US Senate fertilizer hearing: Farmers ‘can’t take much more’ as prices surge
Fertilizer spike adds up to $35/acre for US corn as Iran crisis deepens
