Industrial single-cell protein for feed

01Overview and value chain

Markers: [EC: Feed Additives Regulation (EC 1831/2003) & EU Deforestation Regulation (EUDR) | OECD: Industrial biotechnology & sustainable aquaculture | Regulator: FDA (USA), EFSA (EU), MARA (China)]

Industrial single-cell protein (SCP) is microbial biomass — bacteria, yeast or filamentous fungi — grown by high-rate fermentation of cheap, non-arable substrates and processed into a high-protein feed ingredient. It directly substitutes the two strained legacy protein sources in animal and aquaculture diets: fishmeal, harvested by depleting wild fisheries, and soymeal, whose expansion drives deforestation. SCP carries roughly 60–80% crude protein with a favourable amino-acid profile (rich in lysine and methionine) and high digestibility above 90%, plus nucleic acids and beta-glucans that prime animal immunity. The dominant industrial platform is gas (methane) fermentation by obligate methanotrophs such as Methylococcus capsulatus, which oxidise methane to methanol via methane monooxygenase and assimilate it through the ribulose-monophosphate cycle; alternative platforms ferment CO2 plus hydrogen, or paper-mill and agro-industrial side-streams. By 2026 the sector has moved from pilot to world-scale, with commercial plants displacing imported soy and fishmeal and cutting feed carbon footprints by an estimated 70–90%.

The key directions of industrial single-cell protein are:

1. Methane fermentation (Gas-to-protein): obligate methanotrophs grown on natural gas or biomethane in pressurised loop reactors; the most industrially mature platform, anchoring world-scale plants.
2. Hydrogen/CO2 fermentation (Power-to-protein): hydrogen-oxidising autotrophic bacteria fix CO2 using hydrogen as the energy carrier, coupling SCP to captured carbon and renewable power.
3. Fungal protein from side-streams (Mycoprotein): filamentous fungi such as Paecilomyces variotii grown on pulp-mill and agro side-streams, forming pellets that are recovered by simple sieving, slashing capital and operating cost.
4. Downstream feed formulation: lysis, drying and granulation of biomass into a stable powder blended at 5–20% inclusion into aquafeed and poultry rations.

Sectoral value chain

[Gas / side-stream feedstock] ──> [High-rate fermentation] ──> [Concentration (TFF / centrifuge)] ──> [Cell lysis & drying]
                                            │
                                  (Methanotrophs / fungi)
                                            │
                                            ▼
[Aquafeed & poultry rations] <─── [Feed formulation & extrusion] <─────┘

Value chain levels

Cross-cutting technologies of the sector:

• U-Loop bioreactors: vertical down-and-up loops with a bottom U-bend where hydrostatic pressure rises to several bar, raising methane and oxygen solubility four-to-five-fold over stirred tanks and preventing substrate starvation in fast-growing cells.
• Fungal pelletisation: culturing filamentous fungi so the mycelium aggregates into 1–2 mm pellets that are recovered by mechanical sieving instead of costly centrifuges, cutting capital and operating cost.
• Degassing and safety systems: vacuum degassing of the broth before centrifugation to safely capture explosive residual methane and recycle it to the compressors.

02US

The United States hosts the leading venture-backed methanotroph developers and the commercial partnerships that route gas protein into aquaculture and pet-food markets.

Methanotroph gas fermentation, FeedKind, FDA safety status

• Calysta and FeedKind: Calysta pioneered methanotroph gas fermentation, producing the single-cell protein FeedKind from Methylococcus capsulatus with high nutritional value for aquaculture and pet diets.
• Commercial routes to market: Calysta pairs its production technology with established feed and ingredient distributors to scale FeedKind into global salmon, shrimp and pet-food supply chains.
• Regulatory safety: FeedKind has been recognised as safe for feed use, confirming the biological safety of microbial protein for a broad range of animals.

03CN

China is the principal force in industrial scale-up, hosting the first commercial-scale gas-protein plant and treating microbial protein as a national feed-security priority.

Chongqing FeedKind plant, MARA approvals, soy-import substitution

• Calysseo at Chongqing: Calysseo — the Calysta and Adisseo joint venture — commissioned a commercial-scale gas-protein plant in Chongqing supplying FeedKind to Asia’s large aquaculture sector and displacing imported fishmeal.
• MARA approvals: China’s agriculture regulator (MARA) cleared microbial protein for use in salmonid, shrimp and pet diets, opening multi-tonne contracts with major feed mills.
• Feed-security driver: importing the bulk of its soy, China treats domestic gas-protein production from natural gas or coke-oven methane as a strategic food-security direction.

04EU

The European Union leads on fungal and bacterial protein from industrial side-streams, backed by hard regulatory pressure to decarbonise the feed base.

U-Loop methane protein, Pekilo mycoprotein, EUDR demand pull

• Unibio and U-Loop: Denmark’s Unibio developed a continuous U-Loop methane-fermentation technology for its Uniprotein product and licenses it internationally; with the Saudi Industrial Investment Group it is building a plant of 50,000 tonnes per year, with expansion planned toward 300,000 tonnes per year.
• Enifer and Pekilo: Finland’s Enifer is reviving the historic Pekilo mycoprotein process, fermenting Paecilomyces variotii on pulp- and agro-industrial side-streams; its Finnish plant of about 3,000 tonnes per year is slated to begin supply in 2026, with the product cleared by EFSA for fish and pet feed.
• EUDR pull: as the EU Deforestation Regulation restricts soy from cleared land, demand for local single-cell protein in Europe is rising sharply.

05Leading companies and research institutes

06Tech stack and innovations

The modern SCP plant is built on three engineering pillars that manage gas mass-transfer, biomass recovery and product digestibility.

1. U-Loop fermenters:
   • Stainless-steel loop reactors with high-area heat-exchange jackets, because methane oxidation releases very large heat loads — on the order of 35 MJ per kg of dry biomass.
   • Dissolved-oxygen and methane sensors regulate gas feed inside the loop to keep the mixture outside the explosive envelope.
2. Disc-stack centrifuges:
   • High-g disc-stack separators concentrate cells of roughly 1.05 g/cm³ density into a thick paste while clarified water returns to the fermenter recycle.
   • Continuous solids discharge sustains the high-throughput, steady-state operation that gas fermentation requires.
3. Thermal-lysis reactors:
   • Tubular flow reactors flash-heat the concentrate to around 120–125 °C for tens of seconds, rupturing cell walls and degrading nucleic acids to lower purine load in monogastric animals.
   • The lysed concentrate is cooled before drying, raising protein digestibility for downstream feed use.

07Value chains and production pipelines

Industrial pipeline of methane-to-SCP production in U-Loop bioreactors (ISO 9001 / GMP+ feed safety)

┌───────────────────────────┐      ┌───────────────────────────┐
│ 1. Gas compression &      │ ───> │ 2. Continuous U-Loop      │
│    mixing (CH4+O2+NH3)    │      │    fermentation           │
└───────────────────────────┘      └───────────────────────────┘
                                                 │
                                                 ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 4. Thermal-shock cell     │ <─── │ 3. Degassing &            │
│    lysis (120 °C)         │      │    centrifugation         │
└───────────────────────────┘      └───────────────────────────┘
              │
              ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 5. Spray drying of        │ ───> │ 6. Cooling, packing &     │
│    biomass (180 °C)       │      │    amino-acid QC          │
└───────────────────────────┘      └───────────────────────────┘

Stage 1: Substrate preparation and compression

Natural gas (methane above 95%) is compressed to about 5 bar and blended with sterile air or pure oxygen. Gaseous ammonia is injected as the nitrogen source and pH regulator, and the gas mixture is fed to the bottom spargers of the loop reactor.

Stage 2: Continuous U-Loop fermentation

Fermentation runs as a continuous chemostat in a loop reactor. The aqueous medium carries phosphoric acid, magnesium sulphate, copper salts (cofactor for pMMO) and trace elements. The Methylococcus capsulatus culture circulates around the loop at roughly 2.5 m/s at about 42 °C and pH 6.5, with the dilution rate set so biomass stays near 20 g/L dry solids at near-complete methane utilisation.

Stage 3: Degassing and concentration

The broth is drawn off continuously into a cyclonic vacuum degasser to strip dissolved explosive gases, then fed to a disc-stack centrifuge. Cells concentrate into a wet paste at about 15% dry solids, and the clarified centrate returns to the head of the process for a closed water loop.

Stage 4: Thermal-shock lysis

A high-pressure pump drives the paste into a tubular lysis reactor where direct steam injection flash-heats it to around 125 °C at about 3.5 bar for tens of seconds. Cell walls rupture and intracellular RNA degrades, lowering purine content; the released protein concentrate is then cooled.

Stage 5: Spray drying

The lysed concentrate is sprayed into a drying tower against a counter-current of sterile hot air near 180 °C, forming microdroplets that dry instantly. Exhaust air is held near 85 °C to protect amino acids, and dry particles are recovered by cyclones and bag filters to below about 5.5% moisture.

Stage 6: Cooling, packing and quality control

The powder is fluidised-bed cooled and sent to a silo. QC verifies crude protein (around 70–72% on a dry basis), moisture below 6%, the lysine and methionine profile, and absence of pathogens and heavy metals before the product is packed into bulk bags and shipped to feed mills for salmon, shrimp and poultry rations.