Gas-Fed Single-Cell Protein for Low-Carbon Feed
Producing Single-Cell Protein from Low-Carbon Gases for Next-Generation Feed
Livestock, poultry, and aquaculture feed usually passes through land, water, crops, and long transportation chains before it reaches a feed mill. Every kilogram of feed protein supplied from soy, fishmeal, or by-products carries with it competition over land, water, energy, global input prices, and trade volatility. Gas-based single-cell protein enters the food security discussion from this exact point, because instead of relying directly on farmland or marine resources, it produces microbial biomass from methane, methanol, CO2, and H2. This technology does not promise to eliminate agriculture, but it can separate part of protein production from the constraints of land and climate.
In practical terms, single-cell protein refers to dried or processed biomass from bacteria, yeast, or microorganisms that can serve as a source of protein, amino acids, vitamins, and bioactive compounds in food or feed. In the gas-based route, the carbon feedstock can be methane, methanol, or CO2, while the process energy is supplied, depending on the microorganism, through methane oxidation or H2 consumption. Examples such as FeedKind through the methane route, Solein through the CO2/H2 route, and Proton or NovoTein through the CO2/H2 route show that the idea of producing protein from gas has moved beyond theory and entered the stages of product development, piloting, regulation, and investment. However, each product must be assessed based on its microbe, gaseous feedstock, processing method, and target animal species.
The economic value of gas-based protein is not limited to its crude protein percentage. It must be evaluated in real diets based on digestibility, amino acid composition, quality stability, contaminants, usable energy, animal behavior, and final production cost. A VTT study published in Global Food Security on protein production from direct CO2 and hydrogen-oxidizing bacteria reported that this pathway could deliver several times the protein yield per unit of land compared with soy, while its direct water consumption could be about one-tenth that of soy. These data come from modeling and analysis based on secondary data, and they do not represent the guaranteed performance of all commercial plants, but they are important for understanding the direction of the technology.
How Does Gas-Based Single-Cell Protein Separate the Feed Chain from Land?
The basic logic of this technology rests on converting a gaseous stream or a one-carbon compound into microbial biomass. In the methanotrophic route, bacteria such as Methylococcus capsulatus consume methane as a source of carbon and energy and produce protein-rich biomass. FeedKind is one of the best-known commercial examples of this route and is described in scientific sources related to aquaculture feed as a bacterial protein produced through methane fermentation. This pathway matters from an agricultural perspective because its raw material is not directly a crop, and it can reduce part of the pressure on land, water, and marine resources.
In the CO2/H2 route, the biological model is different, and hydrogenotrophs or hydrogen-oxidizing bacteria play the central role. These microbes use H2 as an electron donor and CO2 as a carbon source, and the quality of the hydrogen source is decisive for climate performance. If H2 is produced using renewable electricity or a low-carbon pathway, the climate claim behind the technology becomes more defensible. But if hydrogen comes from natural gas without carbon capture, the product’s low-carbon status must be assessed cautiously. For this reason, the final evaluation cannot rely only on the origin of the carbon source; the energy source, drying, transportation, and LCA boundaries must also be clearly defined.
Unlike field-based agriculture, producing protein from gas does not directly depend on seasons, rainfall, or soil quality. However, independence from land does not mean independence from infrastructure. A gas bioreactor requires a stable gaseous feedstock, oxygen, minerals, nitrogen, contamination control, drying equipment, safety systems, and mass-transfer management. The advantage of year-round production becomes real only when the supply chains for gas, electricity, process water, nutrients, and biological control are designed reliably.
– International Energy Agency: “Around 35 million tonnes of methane emissions from oil, gas, and coal can be avoided at no net cost.”
The connection between this quote and single-cell protein should not be overinterpreted. Reducing methane emissions in the fossil fuel sector does not by itself prove that producing SCP from methane is economically or climatically viable. Its importance lies in pointing to a broader reality: methane, energy, and carbon are not separate issues in future industrial policy. If a country wants to introduce gas-based protein into the feed chain, it must simultaneously make decisions about methane management, gas pricing, carbon capture pathways, process safety, and the feed market.
How Do Methane, Methanol, and CO2 Differ in Microbial Protein Production?
– The Methanotrophic Route and FeedKind’s Position in Aquaculture Feed
The methanotrophic route is based on methane consumption by methane-oxidizing bacteria. In this pathway, gaseous feedstock enters a bioreactor, and the microorganism produces protein-rich biomass under controlled conditions. In the research file, FeedKind is identified as the most important commercial feed example of the methane route because it has both nutritional data and a traceable regulatory pathway in the United States, China, and Europe. The significance of this example is that the technology has moved beyond laboratory claims and entered the language of regulation, aquaculture diets, and feed trade.
Crude protein percentages in gas-based products must be discussed carefully, because the figures reported for different products, analytical methods, and dry-matter bases are not always the same. For FeedKind, a Frontiers study reported 75.14 percent protein for MBP/FeedKind in black sea bream diets, while older commercial documents from Calysta reported 71 percent crude protein. This difference should not be resolved through simple averaging, because it may result from production batch, testing method, reporting basis, or product version. The scientifically sound conclusion is that protein percentage must be read alongside the source, testing method, and feed application.
– The Methanol Route and the Historical Lesson of Pruteen for Feed Economics
The methanol route is historically associated with Pruteen and serves as an economic warning for the new generation of gas-based proteins. This product was made from methanol and the bacterium Methylophilus methylotrophus, and historical sources report a protein content of 72 percent. Even so, the discontinuation of Pruteen has been attributed to high production costs and its inability to compete with soy and fishmeal. This experience shows that high nutritional quality is not enough for success in the feed market; the product must also compete within the hard economics of bulk feed ingredients.
– Science Museum, United Kingdom, scientific archive: “This product was produced in the 1970s from the bacterium Methylophilus methylotrophus and methanol.”
The lesson of Pruteen for today’s technologies is not that gas-based protein has failed. Rather, it shows that engineering scale and market economics are two different problems. A process may be biologically and technically feasible, but lose its competitive position when soy or fishmeal prices fall. This has direct importance for investors, policymakers, and feed producers, because the revenue model for gas-based SCP must be built around the prices of real substitutes, not only around the product’s technological value. Any project producing this material as a feed ingredient must from the outset include scenarios for competition with soy, fishmeal, and other alternative proteins.
FeedKind Regulations and the Acceptance of Bacterial Protein in the Aquaculture Feed Market
The entry of a microbial protein into animal feed does not depend only on successful fermentation. The feed material must pass through safety, regulatory, and formulation pathways, and each application must be evaluated separately. Acceptance of a product for salmonids cannot be generalized to human food, poultry feed, or feed for all aquatic species. The FeedKind case matters because it shows that regulatory pathways for part of this technology have taken shape in major markets, but each pathway has defined boundaries of use, target species, and inclusion levels.
In the United States, the FDA Center for Veterinary Medicine issued a response under the GRAS notification pathway for the use of FeedKind in salmonid feed at up to 18 percent of the diet. The important point is that the FDA itself states in the response that it did not make its own independent GRAS determination and that responsibility for compliance remains with the company. Therefore, the precise way to describe this event is as a “no further questions” response within the GRAS notification framework, not as an absolute claim of full and independent FDA approval. This level of precision is necessary in technical writing, because regulatory exaggeration can distort investment decisions and market trust.
– FDA Center for Veterinary Medicine: “However, the agency has not made its own determination regarding the GRAS status of this use in animal food.”
In China, FeedKind was approved in 2023 for use in aquaculture feed, a commercially important development because China is one of the major markets for alternative protein uptake in aquaculture. In Europe, Regulation No. 68/2013 lists protein obtained from Methylococcus capsulatus under entry 12.1.2 in the feed materials catalogue, and the 2022/1104 amendment updated the naming related to single-cell protein from Methylococcus capsulatus. This evidence shows that, at least for the methanotrophic route, a defined regulatory language exists in some reference markets.
Clear boundaries also matter for other pathways. In AGRN 33, the FDA reviewed dried biomass from Methylobacterium extorquens for a certain level of use in aquatic crustacean feed and referred to AGRN 26 for feed for finfish. This case relates to the methanol or methylotrophic route and should not be treated as equivalent to the CO2/H2 or methanotrophic routes. The practical conclusion is that single-cell protein is a broad category, but each microbial species, gaseous feedstock, processing method, and target animal must have its own technical and regulatory file.
Nutritional Metrics for Single-Cell Protein in Livestock, Poultry, and Aquaculture Feed
Evaluating gas-based SCP for feed starts with the simple question of how much protein it contains, but it does not stop there. FAO guidance on aquaculture feed ingredients emphasizes the analysis of proximate composition, amino acids, fat, energy, antinutritional factors, contaminants, digestibility, and cost-effectiveness. This framework becomes even more important for microbial protein because the product is made through a nontraditional biological pathway, and feed mills need to know how the new material behaves in a diet. If the chemical composition is appropriate but digestibility or supply stability is weak, its industrial value will be limited.
Aquaculture feed studies have shown that replacement levels must be evaluated step by step in experimental diets. In a study on largemouth bass, experimental FeedKind diets were formulated at inclusion levels of 3, 6, and 9 percent, while the fishmeal share was reduced from 42 percent in the control diet to 29, 26, and 23 percent. The trial lasted 10 weeks, and this design shows that replacing a new feed material is not a single-variable decision. Researchers must evaluate the combined effects of SCP level, fishmeal reduction, growth, health, feed conversion ratio, and carcass quality in real diets.
Digestibility must also be measured using a precise protocol. An Aquaculture study on bacterial protein meal in Atlantic salmon emphasized that at least 14 days of adaptation are required before feces collection for digestibility measurement. These methodological details matter directly for pilot designs, because a rushed result can make a feed material appear either too positive or too negative. For Iran, or any other emerging market, feed trials should from the beginning be designed with a clear adaptation period, control group, replacement level, and performance indicators.
The amino acid profile of FeedKind has been described in scientific and commercial sources as balanced and comparable to fishmeal, but final decisions should rely on study-based data. Crude protein figures of 71 percent, 72 percent, 73 percent, and 75.14 percent reported across different sources for gas-based or historical products come from different products and methods and should not be merged into a single average. The correct metric for a feed mill is that every product batch should be accompanied by certificates for composition, microbial quality, moisture, contaminants, and digestibility. Otherwise, high protein can be an attractive but insufficient number for purchasing decisions.
Economies of Scale and Investment Risk in Gas-Based Feed Protein
Gas-based protein is scientifically attractive, but economically it enters one of the most difficult commodity markets. Livestock, poultry, and aquaculture feed is a high-volume, margin-sensitive market, and any new ingredient must compete with soy, fishmeal, yeast protein, insect protein, and by-products. The Pruteen experience showed that even a high-protein material may leave the market if its price does not fit into the competitive cycle of conventional ingredients. Therefore, the main investment question is not only whether production is possible, but whether pricing can remain durable at industrial scale.
Recent investment data show that private companies, venture capital investors, and energy firms have paid attention to this field, but that attention does not mean the risk has decreased. In 2024, NovoNutrients announced an $18 million Series A financing round, including $10.3 million in new capital and the conversion of $8 million in SAFE notes. The same research file shows that roughly one year later, the company entered an Assignment for the Benefit of Creditors process and asset sale. This sequence sends a clear message to the gas-based protein market: the gap between demonstrating the technology and sustaining the financial performance of a plant is the high-risk zone where many industrial biotechnology ventures stall.
Public capital and patient capital play a complementary role in this technology, because many projects need pilot and demonstration stages before reaching mass markets. In 2021, the Finnish Climate Fund granted Solar Foods a €10 million capital loan to begin commercial production of Solein, and Deep Branch received €2.5 million from the EIC Accelerator for its CO2-to-feed project. Woodside also committed up to $3 million to build and operate NovoNutrients’ pilot system, with payments tied to milestones. These examples show that staged, public, and conditional financing matters for moving from laboratory to factory.
– CORDIS project report, European Union: “This pilot is designed to provide the operational capacity needed to develop protein applications in animal feed.”
The distinction between pilot, demonstration, and industrial production is critical for animal feed. Producing a few hundred kilograms per month is valuable for application development, diet trials, and sample product creation, but it is not enough for the livestock and poultry market, which operates at high volumes. Even the 160-ton-per-year capacity reported for Factory 01 in the food-oriented Solein pathway shows the distance between demonstration production and the high-volume feed market more than it solves the feed ingredient problem. As a result, investors must include not only biotechnology, but also energy cost, drying, quality control, offtake guarantees, the permitting route, and competitor pricing in the financial model.
Iran’s Conditional Pathway for Localizing Gas-Based Single-Cell Protein
From the perspective of gaseous feedstock, Iran has a clear structural asset. According to EIA data, Iran’s proved natural gas reserves are reported at about 1,200 trillion cubic feet, or approximately 34 trillion cubic meters. This figure only indicates potential gaseous feedstock capacity and should not be interpreted as evidence that an SCP industrial chain already exists in the country. A gas advantage becomes an industrial opportunity only when it is combined with reliable electricity, bioreactor safety, access to nutrients, fermentation know-how, industrial drying, and a feed approval pathway.
Iran’s aquaculture market is also significant from the perspective of feed demand, although the available data in the research file are old and must be used cautiously. FAO’s fisheries and aquaculture profile for Iran reported that aquaculture production rose from 27,000 tonnes in 1990 to 320,200 tonnes in 2014, accounting for about 34 percent of total fisheries production that year. This historical trend suggests that aquaculture feed could be one of the first areas for testing and accepting microbial protein, since globally FeedKind and some CO2/H2 projects are also linked to aquaculture feed applications. However, entering this market requires domestic performance data and formulations tailored to target species.
For Iran, the logical path does not begin with a large, high-risk factory. It begins with an industrial pilot located near a controllable gaseous feedstock source. Siting the project near a gas refinery, petrochemical plant, biogas unit, or carbon capture system is technically conceivable because it simplifies access to gaseous feedstock and energy. However, such siting creates value only if the final product can pass feed trials and market acceptance. A successful pilot must produce not only kilograms of product, but also data on composition, digestibility, safety, batch stability, energy cost, and the response of feed mills.
Currency and technology risks must also be included in Iran’s decision-making. On one hand, reducing pressure on imported protein ingredients is attractive for the feed chain, and linking this opportunity to the country’s gas advantage can give industrial policy a clearer direction. On the other hand, gas fermentation equipment, compressors, process control systems, safety management for H2/O2 or CH4 mixtures, dryers, and specialized feed tests may themselves depend on technical know-how and imported equipment. Therefore, real localization will take shape only when the project does not rely solely on access to gas and instead builds the engineering, regulatory, financing, and market chain at the same time.
How Does Low-Carbon Single-Cell Protein Become an Investment Decision?
An investment decision in gas-based single-cell protein must pass through three simultaneous questions. First, can the selected microorganism and gaseous feedstock produce biomass with stable composition, sufficient protein, acceptable microbial quality, and acceptable digestibility? Second, can the product replace part of soy or fishmeal in real livestock, poultry, or aquaculture diets without reducing performance and at a defensible price? Third, are the regulatory pathway, financing, process safety, energy supply, and sales market clear enough for the project to move from pilot to factory?
For the Iranian market, the cautious and practical answer is that gas-based protein is a conditional opportunity, not a ready-made solution. Gas reserves and the historical growth of aquaculture create a basis for industrial study, but they are not sufficient conditions for success. A defensible pathway must pass through a limited pilot, standardized feed trials, selection of target species, competitor price analysis, life-cycle assessment, and a staged financing model. If this chain is built carefully, single-cell protein from methane, CO2, and hydrogen can move from a technological idea into one of the future tools of low-carbon feed.
