Counting Deep Branch's EIC Accelerator Results on CO2 Feed Protein

Deep Branch Biotechnology Ltd, a Nottingham start-up incorporated in July 2018, grows bacteria on carbon dioxide and hydrogen instead of sugar and dries them into Proton, a single cell protein meant to replace fishmeal and soy in fish and poultry feed. The European Commission's list of the May 2020 EIC Accelerator pilot winners names it as a grant-only winner of the Green Deal cut-off, with no other company listed for the same project. According to CORDIS, the Proton project ran from 1 October 2020 to 30 September 2023 with a total cost of €3,558,315 and an EU contribution of €2,490,820.50, to build a pilot plant making more than 200 kg of Proton a month, validate its nutrition, design a demonstration plant and secure patents.

Six years on, the plant exists and the patent was granted. But the plant started producing almost a year after the EU project ended. In July 2024 the business was transferred to new companies called Aerbio, and in June 2025 the original UK company went into members' voluntary liquidation, according to Companies House.

What Happened to Deep Branch

The company's last accounts, for the year to 31 July 2024, explain the handover. Under a September 2023 agreement with Sundaenget Invest ApS, Fredericiagade Holding ApS and DSM Venturing, Deep Branch gave the two Danish companies an option to make it sign an asset transfer agreement. They exercised it on 17 May 2024. On 17 July 2024 they and Novo Holding A/S waived repayment of a convertible loan, and on 19 July 2024 the parties agreed which assets would move to Aerbio A/S, Aerbio UK Ltd and Aerbio BV. On the same day Deep Branch sold its Dutch subsidiary, Deep Branch B.V. The accounts were filed with Companies House in June 2025. The Dutch subsidiary now trades as Aerbio B.V. under the same Chamber of Commerce number, according to North Data.

FoodNavigator described the deal in August 2024 as a management buyout backed by existing shareholders. Kaspar Kristiansen became chief executive, cofounder Rob Mansfield chief technology officer, and Lars Topholm chair. The Danish register shows that the parent, now Aerbio Group A/S, was registered in Roskilde in 2024 as "DBB BidCo ApS", according to North Data. Aerbio therefore acquired the Deep Branch business through a vehicle set up for the buyout, not as an outside buyer. The price paid for the assets is not public.

The UK shell went into liquidation in an orderly way. All five directors swore a declaration of solvency on 23 May 2025, listing £45,805 in cash and a £1,721 VAT refund as its only assets. Shareholders resolved to wind the company up on 17 June 2025 and appointed FRP Advisory as liquidators, according to Companies House. The liquidators' report to 16 June 2026 says no creditor claims were received and a final distribution to shareholders is still to come. The company has not yet been dissolved. Its website, deepbranchbio.com, did not respond when checked on 18 October 2026.

How Proton Is Made

Most single cell protein is grown on sugar or methane. Deep Branch used hydrogen-oxidising bacteria, which take their carbon from carbon dioxide and their energy from hydrogen and oxygen. The company's European patent EP4138568B1, granted on 29 May 2024, claims a continuous process with bacteria of the genus Cupriavidus that yields biomass of at least 65% protein by dry weight at more than 10 grams per litre per day. CORDIS lists the filings behind it, a UK priority application of 24 April 2020 and an international application of 26 April 2021, on the project's results page.

The pitch was that Proton could take carbon dioxide from industrial emitters and compete on price with fishmeal and soy. The company tested its mobile pilot unit with purified carbon dioxide at industrial sites in the United Kingdom and the Netherlands, according to the CORDIS report. In 2025 Mansfield told AgFunderNews that raw flue gas from the Drax power station had also worked but was not the preferred source because of impurities. He said a contract research trial had found digestibility comparable to fishmeal with substantially higher protein content. That trial has not been published. Mansfield's claim that "we can compete on price with all high-quality protein ingredients" has not been backed by any published production cost.

The EIC Project: Promised Against Delivered

CORDIS gives four objectives: a pilot plant producing more than 200 kg of Proton a month, full nutritional validation, a completed design for a demonstration plant, and IP protection. The objective also said that within five years Deep Branch wanted a commercial plant co-located with an industrial emitter, producing more than 50,000 tonnes of single cell protein a year. Of the EU contribution, €2,006,788 went to Deep Branch Biotechnology Ltd and €484,032.50 to its Dutch linked third party, listed on CORDIS today as Aerbio BV in Geleen.

The final report covers the period to 30 September 2023, the project's last day. It says the pilot plant had moved through design and procurement into installation at the Brightlands Chemelot Campus in Geleen. Installation was due to finish at the end of 2023, with commissioning and the first production campaign in the first quarter of 2024. In the meantime, small volumes made in the Nottingham lab were used to check the product's nutritional value. In November 2020 the company expected to open the plant in the second quarter of 2021, according to Innovation Origins. The Fish Site reported the plant's launch on 27 August 2024, producing about 200 kg of Proton a month. FoodNavigator reported that it was fully operational after initial delays. So the plant met its target capacity, but almost eleven months after the EU project had ended.

1. Pilot plant, over 200 kg Proton a monthLateNot finished when the project ended in September 2023; about 200 kg a month by August 2024 (The Fish Site).
2. Full nutritional validationPartialLab batches tested; an unpublished contract trial benchmarked Proton against fishmeal (AgFunderNews). No salmon or poultry trial results published.
3. Completed demo plant designNot achievedEngineering of a 250-tonne-a-year facility was still under way in August 2024; no completed design has been announced.
4. IP protectionDeliveredEuropean patent EP4138568B1 granted 29 May 2024 (Google Patents).
5. Commercial plant of 50,000+ tonnes a year within five yearsNot achievedNo commercial plant; Aerbio expected its first large-scale factory in 2027 (M&A Insights).

Money In, Losses Out

Deep Branch raised an €8 million Series A in March 2021, led by Novo Holdings and DSM Venturing with Total Carbon Neutrality Ventures and Barclays Sustainable Impact Capital, according to Novo Holdings and The Spoon. The money was to finish the scale-up hub in Geleen and design a first commercial plant, with Norway as a leading location and commercial production planned for 2023. Novo said the round came on top of €4 million in UK and EU grants. One of those grants was the £3 million Innovate UK project REACT-FIRST, a 10-partner consortium with BioMar, AB Agri, Drax and Sainsbury's to test Proton in salmon and poultry feed, according to the University of Stirling.

The group accounts on Companies House show losses rising from £0.91 million in the year to July 2021 to £5.68 million in the year to July 2024. The auditors flagged a material uncertainty about going concern in both the 2022 and 2023 accounts. In early 2023 existing investors put in bridge financing of about €2.6 million. The 2023 accounts said further investor money depended on meeting a technical target the company called "stoichiometry" and was partly at the investors' option. In the 2023/24 year shareholders put in another £4.9 million in new shares, but cash at the year end was £96,676.

Aerbio Since the Transfer

Aerbio launched a Series A of up to €50 million in September 2024 to build a demonstration plant, aiming to close in the fourth quarter of 2024, according to Feed & Additive. No close has been announced. In September 2025 M&A Insights reported that Aerbio was still looking for investors, that earlier rounds had raised more than €36 million, and that it hoped to list within three years. AgFunderNews reported in June 2025 that Mansfield had moved to Copenhagen to build a demonstration-scale facility aiming for one tonne of Proton a day in 2027. In August 2024 FoodNavigator reported the demo plant at about 25 tonnes a year and due online by 2026, while The Fish Site gave 250 tonnes a year for a planned "Market Launch Facility". The sources do not agree, and none confirms that construction has started.

The Aerbio companies are still active. Aerbio BV and Aerbio A/S are partners in two EU projects: the Horizon Europe project UNICO2RN, led by the Belgian research institute VITO, running from June 2025 to May 2029 with €1,306,125 for Aerbio BV and €557,812.50 for Aerbio A/S, and the bio-based industries project SynoProtein, with €344,325 and €69,000. North Data shows Aerbio Group A/S raising its share capital three times between July and October 2026, to DKK 830,016. The amounts invested behind those increases are not public.

Why It Matters for Europe

The EU livestock sector is "critically dependent on imports of plant-based proteins for animal feed", mainly soy from Argentina, Brazil and the United States, according to a European Parliament briefing that names microbial protein as one way to diversify supply. The Commission's own feed protein balance found the EU produced only 26% of the oilseed meals it used, as reported by the Irish Farmers Journal. A process that turns waste carbon dioxide and hydrogen into feed protein fits both the Green Deal round it won and the push for strategic autonomy in feed. But that only holds if the product reaches commercial volumes and prices. After six years it has reached 200 kg a month in a pilot plant.

The Verdict

Deep Branch's liquidators, Aerbio and the EIC were not asked for comment for this article. It is based entirely on public records and published statements, linked throughout.