California-based Switch Bioworks is pioneering an approach that enables engineered microbes to first compete and establish themselves on plant roots before switching on nitrogen fertilizer production, addressing a major challenge in this segment of the biologicals market, claims founder Dr. Tim Schnabel.
AgFunderNews (AFN) caught up with Schnabel (TS) at the SynBioBeta conference to find out more…
AFN: What problem are your genetic switches solving?
TS: As soon as you engineer a microbe to release nitrogen fertilizer, it’s a very energetically expensive process, and that microbe is going to be using all of its energy making that fertilizer as a resource for the plant, rather than using that energy for itself [to reproduce and colonize plant roots].
And what that means for the microbe is that it becomes uncompetitive compared to the native microbes that live in the soil that are not making ammonia for plants, and so the engineered microbes are getting out-competed. After a couple of days, they’re gone, because the un-engineered native microbes are just healthier. So that’s kind of a problem.
The way to get around that is to engineer the microbes to first compete with the native microbiome and establish themselves. And then, once they’ve established themselves, a genetic switch turns on, and now they’re producing ammonia.
So we kind of get the best of both worlds: healthy, competitive microbes and engineering to get the ammonia out into the plants.
AFN: What triggers your genetic switches?
TS: The switch lives in the DNA of the microbe and it detects changes in the environment that trigger ammonia production. We’re in the product development phase right now, so there are several switches that could be the best product, and we don’t yet know which one it is. So we’re working on many switches in parallel.
The question is, which is best? And then how do you precisely tune it to do what you want at the right time?
AFN: Can you use the same approach to trigger microbes into producing other substances?
TS: Yes! We’re thinking about this as a platform. What else do we want a microbe to make? And what would be the best switch that we could put in front of it to have it produce that [substance] in a controlled manner?
Image credit: Switch Bioworks
AFN: Do you have one microbe or a mixture?
TS: If you have a community or a consortium of strains that each occupy different parts of the plant roots, you can make more fertilizer overall, so our initial product will have at least three strains.
But then we’re thinking of going to 4, 5, 6, 7 strains to see how high we can go, as at some point, there will be diminishing returns where the added cost of manufacturing one more strain isn’t worth the extra output that it generates.
The diversity of strains that we’re using in our product has another big advantage. Biologicals are often criticized for their unreliable performance across different soils, so what if we could build a community of microbes that is built in a way to be resilient and adaptive, to function across different soil types?
Let’s say we have five strains and we want to make our products work across two different soil types? It could be that three of those strains do well in one soil and the other two do well in the other soil and they kind of help each other out. It’s like an insurance policy. In farming, everything is about reliability.
AFN: How are the microbes applied to the crop?
TS: Our initial go-to-market is an in-furrow formulation but we’re keeping a really close eye on seed lubricants… can we apply dry powder microbes to the seed right before planting? Seed coating would be the Holy Grail, but the challenge there is shelf-life.
AFN: How economically viable is your tech?
TS: One of the big things about biologicals is their inherent scalability. If you think about the fertilizer industry, it’s making fertilizer. We actually don’t make fertilizer. We make the thing that makes the fertilizer, so we have to produce much less. Instead of 100lbs it’s just ounces of powder, and that’s cheaper to produce.
We have a techno-economic analysis that estimates the product to cost around $1 for manufacturing per acre.
AFN: How much money have you raised?
TS: We closed a $17 million seed round last summer, so we’re okay for now, for which I am very grateful, because it is a very tough market.
In ag biologicals, because there are so many companies, investors are looking for differentiation. What is different about our product? And so the idea behind not just engineering, but engineering with control, and having genetic switches is really interesting to them.
And furthermore, we really understand the mechanism of action. It’s not this kind of silver bullet microbe that makes your crops grow better but no one really knows how.
AFN: What markets are you focusing on?
TS: Initially, we’re targeting corn in the US, that’s the biggest market for nitrogen fertilizer. But the principle of switchable ammonia release could apply to any crop in any region. The question is do you need a different host microbe that does well on that plant in that soil? And do you need a different switch that turns on under the right conditions?
We also have support from the Gates Foundation to build our solution for Sub Saharan Africa. The reason that is exciting to me is that farmers there can afford much less fertilizer. And so if you’re able to produce about 40lbs of nitrogen with a biological product, in the US that will replace maybe 25% of fertilizer. But in Africa, that’s going to have a huge impact, potentially doubling the amount of food that people can grow. And so those projects from an impact standpoint are just really, really meaningful.
AFN: When might you hit the market?
TS: We were founded in 2022 and have spent the last three years in the product development cycle. We’re putting products in the greenhouse and the field starting this year, and then we’ll keep doing that every year after that. We’re estimating to be commercial in 2028.
AFN: Will microbial fertilizer options ever completely replace synthetic fertilizers?
TS: I would love to believe that they can fully replace synthetic fertilizer but I don’t think it’s possible. I think the cap is at about 50% replacement at yield parity. Could we go beyond that? That would probably require engineering the plant to release more sugar or some other innovation that I’m not even thinking about.
Now 40% is the upper end. But I think for us to be successful, we don’t have to be at 50%. Just replacing 25% of nitrogen fertilizer at yield parity would be game changing.
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