The Copenhagen biotech startup making protein from thin air

Things are moving fast at Copenhagen-based biotechnology company Aerbio. The startup has its roots in the UK but recently relocated to the Danish capital after several years operating out of the Netherlands. Unfortunately, that move precipitated the exit of CXO and co-founder Pete Rowe, who The Engineer had originally spoken to about the company back in February. Thankfully, fellow co-founder and CTO, Rob Mansfield, was able to provide an update in the wake of the executive shake-up. 

“The dream scenario is we’re going to consolidate the company here (Denmark) and everyone comes with us and it’ll be great, yeah?” Mansfield explained. “And then the reality is that people have lives outside of their work, even in the intensity of a startup. Pete’s got a couple of kids down in Leiden, so this is a bigger lift for him than it would be for me.”

Mansfield and Rowe met more than decade ago at the University of Nottingham where they were both exploring a niche area of biotechnology known as gas fermentation. Throughout their PhDs, the pair discovered how the technique could be used to make valuable products like biofuels and chemicals from a wide variety of inputs.

Having gone their separate ways at the end of their studies, they later reconnected at a gas fermentation conference in London. The first thing that struck them was the lack of industry interest, with academics making up about 95 per cent of attendees.

“We said ‘what an absolute waste of the four years of our PhD to have to have such little industry representation at a conference like this’,” said Mansfield.  “What can we do about that? Or who should we blame for that? And we pointed the fingers squarely back at ourselves.”

Tapping that frustration and spotting a market opportunity, they set up Deep Branch in 2018 with Bart Pander (Deep Branch would later be folded into Aerbio when it was founded in 2024) to explore commercial applications for gas fermentation. The company’s core technology process sees microbes in bioreactors feeding off carbon dioxide and hydrogen instead of sugar.

Dissolving the gases with oxygen into a water-based solution enriched with nitrogen and electrolytes provides an ideal environment for the microbes to flourish. The result is a highly sustainable protein called Proton that can be produced uniformly at scale.

“Proton is the protein ingredient that comes out of our reactors,” said Mansfield.

“What’s cool about it is that the gaseous inputs are available at a high degree of consistency, at volumes that way, way, way, surpass that of sugar.”

Knowing they were on to something, the Deep Branch team then signed up to a Nottingham business accelerator. Having been confined to the lab for virtually all their careers, they quickly found themselves a long way outside their comfort zone - something which Mansfield now recognises the value of, despite the tough learning curve.

“It dragged us kicking and screaming…out of the world of academia - and even just R&D style industry - into actually the commercial world of ‘this is what it takes to build a business’,” he said.

“For six months it was sort of pens down, phones up, and just calling customers, finding where the market fit was for what we thought our product was.”

Though sustainability was a key driver behind the technology’s development, that didn’t automatically align with market demands.

“What became quickly obvious was that people are not super interested in sustainable protein per se, but they are bloody interested in protein and getting more of it,” said Mansfield.

That initial tranche of reluctant phone calls led the team towards the aquafeed market – high concentration protein products for fish farming. More than 3 billion people depend on fish as a primary source of protein, with average per capita consumption currently around 20kg per year.

By the end of this decade, almost 60 per cent of fish for human consumption is expected to come from fish farming, or aquaculture. Aerbio’s feed product is claimed to have a 90 per cent smaller carbon footprint than traditional protein sources for the sector. And while sustainability may not currently be a key market driver for aquafeed, it is likely to become increasingly important. In the meantime, the tailored nature of Aerbio’s technology process means that the company can rely on other selling points.

“It’s basically one product that can fit into multiple verticals,” said Mansfield. “Conveniently, or through good luck or good judgement, it fits very nicely with the amino acid requirements of fish - salmonids in particular.”

Due to the particular needs of aquaculture and the anticipated growth in farmed fish, the aquafeed market was also more open to new ideas compared to more conservative areas of agriculture.

“There’s plenty more fish in the sea. Except that there’s not,” said Mansfield. “Or at least there’s a finite catch every year…the reality is you can fish a bit more one year, but you’ll penalise yourself the next.”

Improvements in aquaculture offer one obvious way to increase the overall quantity of fish for human consumption. Bespoke, higher protein feeds are the most direct way of doing that. According to Mansfield, the concentrated soy products widely used in livestock agriculture don’t quite meet the needs of the aquaculture industry.

“They need basically above 70 per cent protein,” he said.  “Soy - even the concentrated soy - didn’t really meet that, so they’re desperately trying to find ways to fill that gap and they were willing to pay for it.”

Using Proton as the high protein base ingredient, Aerbio is already working with aquafeed producer BioMar to develop salmon products, as well as AB Agri - the UK’s largest producer of poultry feed - to explore products for broiler chickens. According to Mansfield, the feed requirements are similar, but with some subtle differences dictated by the eating habits of each species.

“A good protein for a fish and a good protein for a chicken are not worlds apart,” he explained.

“It’s just that chickens will eat more, and because of that you can feed them a less perfect diet, as it were. The fish are a bit more precious. They limit how much they actually choose to eat, and so you need to get the balance right in what you do feed them.”

Aerbio’s pilot plant in the Dutch town of Geleen has been producing around 200kg of Proton a month since August 2024, designated for feeding trials and food application development work. The recent move to Denmark will allow the company to tap into the country’s high-tech food manufacturing sector, with plans to build its bioreactor out to demonstrator scale.

“The demo is currently set to be deployed just west of Copenhagen at Roskilde, where the music festival is,” said Mansfield. “We’re aiming for a nameplate capacity of about one tonne per day.

“That is a couple of orders of magnitude lower than commercial facilities, which will themselves be a series of modules – copy-paste bioreactors - each capable of in the region of 10,000 tonnes per year.”

According to Mansfield, the new plant is due to be operational by 2027 and the pathway to achieving commercial scale is clear. Ramping up to bigger numbers is essential if the technology is to have its intended impact. 

“If you are going to tackle environmental or ecological challenges, you have to be operating at meaningful scales,” he said. “So if you can replace hundreds of thousands of tonnes of feed protein, you’ve actually made a real difference there.”

Animal feed – and aquafeed in particular – is very much the focus for now. However, protein for human consumption is also on the agenda, albeit further down the line and with much higher regulatory hurdles to overcome. Rather than entering the rapidly growing and highly competitive meat-substitute sector, Mansfield sees a more likely opportunity for a protein ingredient that could be used to bulk out cakes or breads. 

“We’ve got a number of ideas in that space…but there’s a very different commercial roadmap there,” he said. “The nice thing about going animal feed first is we can address it today with no real regulatory barriers between us and a product on the market.

“We’re also very conscious of split focus. Small team. The temptation is everywhere, yeah, but if you can do one thing right, that’s generally better than doing lots of things badly.”