Single Cell Protein- Production, Source, Importance, and Applications

Single Cell Protein

Edited By Irshad Anwar | Updated on Jul 02, 2025 05:41 PM IST

Single-cell protein: Proteins are an essential component in nutrition for overall well-being. Experts are exploring sustainable alternative solutions to meet future protein demands. Meat and soy—the traditional sources of protein- are also becoming more unsustainable because of their carbon footprint. Here comes Single Cell Protein (SCP), an innovative solution with the potential to solve the worldwide protein deficiency effectively and sustainably. Single cell protein is a topic of the chapter Strategies for Enhancement in Food Production in Biology.

This Story also Contains

What is Single Cell Protein -SCP?
Sources of Single-Cell Protein
Single Cell Protein Production
Importance of Single-Cell Protein
Applications of Single Cell Protein
Advantages and Disadvantages of Single Cell Protein
Challenges and Future Prospects

Single Cell Protein

What is Single Cell Protein -SCP?

Single Cell Protein Definition— Protein obtained from microbial biomass such as yeast, bacteria, algae, fungi, etc., is defined as single cell protein. This microbial protein is known for its high protein content and potency and is a safe nutritional supplement in human and animal diets. In this view, SCP provides a reliable protein source that satisfies the nutritional requirements of an increasing population, reduces environmental pollution and takes the place of traditional proteins.

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Sources of Single-Cell Protein

The extraction source of SCP from algae, yeast, fungi, and bacteria is an excellent choice due to the microbial protein yield.

Bacteria

Methylophilus methylotrophus and Bacillus subtilis are often employed for SCP production because of their fast growth rate and high protein content.

Algae

Algae belonging to species such as Spirulina and Chlorella are among the widely studied species for SCP from algae, having notable high protein content and nutrition.

Yeast

For SCP production, yeast species like Saccharomyces cerevisiae and Candida utilis are used due to their high substrate-to-protein conversion yield.

Fungi

Known for its long and increasingly recognised diversity hosts, the choice of Fusarium venenatum to Aspergillus niger is a vast reservoir of SCP protein and is applicable for varying uses.

A few examples of Single Cell Protein are discussed below.

Microorganism	Protein (%)	Lipid (%)	Carbohydrate (%)	Nucleic Acid (%	Ash (%)
Bacteria	50-8-	4-7	8-14	8-12	3-7
Algae	40-60	10-20	15-25	4-8	8-10
Yeast	45-55	4-7	20-30	6-10	5-8
Fungi	30-45	5-10	30-40	5-10	8-10

Single Cell Protein Production

The production process of single cell protein is divided into the following steps:

Selection of Microorganisms and Substrates

The single cell protein production process is a multi-step process that starts with the biotech companies choosing the right microorganisms and substrates. The suitable organisms are those that grow fast and produce a high protein content. The most common substrates used for SCP production include agricultural wastes and residues, industrial by-products and some carbon sources such as methane or CO2.

Microorganisms and their substrate preferences.

Bacteria

Microorganism	Substrate Preferences
Methane, agricultural waste
Algae	CO2, sunlight
Yeast	Industrial by-products, sugars
Fungi	Agricultural waste, industrial by-products

Fermentation Process

The fermentation process is used to grow specific microorganisms under specific conditions for affordable production of SCP. Such conditions include temperature, pH and oxygen levels. The same is illustrated below:
1. Inoculation: Putting microbes into the soil
2. Fermentation: Controlled condition for microbial growth and protein production.
3. Recovery: Removal of microbial organisms from growth medium.
4. Post-Harvest Treatment: Drying and refinement of fermented SCP, processing it into edible protein and energy.

Harvesting and Post-Harvest Treatment

SCP is produced as a metabolic product of microorganisms,i.e., microbial protein, growing in an appropriate medium under aseptic conditions. After fermentation for SCP, the cells are separated from the medium and harvested as SCP. They are next dehydrated and then cleaned to an eatable state. The following steps are guidelines to make sure the end product of the SCP is safe to feed, nutrient-balanced, and palatable.

SCP Processing for Food

The SCP is further processed to improve its nutritional value as well as flavour and texture. It could involve the use of enzymes, flavour enhancement, texturising, etc to make SCP suitable for different food applications.

Importance of Single-Cell Protein

The importance of single cell protein is described below-

Nutritional Value

Based on the current study, there are many nutritional benefits of SCP. It provides all the essential amino acids in forms and concentrations that are nearly similar to that of conventional protein sources. SCP is a rich source of protein; SCP can contain more protein and nutrients than even meat or soy.

Environmental and Economic Benefits

SCP production incorporates the use of waste products, meaning that it reduces pollution since the products are useful as protein sources. The SCP production method is more effective than animal farming and has to become an integral part of future models of food safety. Therefore, the environmental benefits of SCP justify its need to be utilised.

Health Benefits

SCP is very useful in fighting malnutrition as it provides essential nutrients. It also has nutritional benefits such as reducing cholesterol and enhancing the gut of human beings and animals and therefore can be consumed by both.

Applications of Single Cell Protein

Some applications of single cell protein are-

In Human Nutrition

SCP is incorporated in various food products, functional foods, and nutraceuticals, thus being in the common diet of mankind. Examples of SCP-based products include protein bars and shakes as well as meat-substitute products.

Animal Feed

SCP in animal feed has valuable effects on growth promotion and feed consumption for livestock, poultry and fish is important for the animals. The SCP production process is fully efficient, right from the procurement of materials and even animal feeds.

Industrial Uses

Apart from the food industries, SCP has prospects for use in different fields such as pharmaceuticals, cosmetics, and bio-energy, which confirm the high scalability of the use of the invention.

Advantages and Disadvantages of Single Cell Protein

The advantages and disadvantages of single cell protein are summarised below-

Advantages

It features a high protein content and a high production rate due to the utilisation of enzymes.
The unique characteristics of waste materials, their exhaustion, and proper use minimise their effect on the environment.
Another key issue that needs to be addressed is having a sustainable and scalable production process.
Specially designed with the ability to provide nutrition solutions regarding certain diets.

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Disadvantages

Due to the high content of nucleic acid, necessary means are required to reduce it for human consumption.
The initial setup of the production is very expensive.
While there are individual applications to have the novel food approved for use as human food, there are also regulatory measures that one has to overcome to gain approval.
Additional issues related to sensory acceptance, taste and texture.

Challenges and Future Prospects

The challenges faced by single cell protein are-

Technical and Regulatory Challenges

The challenges of SCP production include issues of contamination, scalability, and the regulatory processes that are required before SCPs can be produced and used in society. These problems must be solved to achieve the necessary vast-scale deployment of SCP technologies.

Future Trends

Newer and improved methods in SCP production technologies continue to evolve and this may lead to increased efficiency of the product and its uses. The analysis of future perspective evinces the increasing importance of SCP objectives in worldwide nutrition and sustainable development initiatives.

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Biofortification	Agriculture fertilizer
Animal husbandry	Agricultural implements
Tissue culture	Biocontrol agent

Frequently Asked Questions (FAQs)

1. In what way could single-cell protein help in meeting the food security of the world?

SCP may be used to look into global food security and offer a solution by supplying protein in a manner that is sustainable and productive. It uses smaller land and water resources than conventional farming; and can be produced from the by-products of agriculture and industries.

This also makes SCP production to be friendly to the natural environment and cheaper to carry out. Also, SCP can rise sufficiently to meet growing protein expectations, especially in those countries where there is a problem with agricultural areas.

2. Explain the fermentative production of SCP using methane utilising bacteria.

Methane-utilising bacteria are grown in bioreactors with methane to be used as the carbon source. Refrigeration is the process of keeping chemical reactions in their ideal state for bacterial development. The biomass is subsequently collected, washed and dried, and is then processed to yield a protein-rich powder. It makes the production process of SCP for food and feed continuous and scalable with improvements.

3. What are the main challenges that are linked to the commercial production of SCP?

The ordinary production of SCP has issues of high production costs and stringent purification process to avoid compromise on safety. Consumer acceptance of MDP can be hindered by people’s inability to accept microbial-derived proteins. There are regulatory challenges as well because safety and other standard requirements for SCP are very high. The challenges are; The third challenge is how to increase production and meet capacity while at the same time increasing quality and how to deal with large scale equipment.

4. In what respect is single-cell protein advantaging performing over the traditional livestock farming in terms of environmental influence?

The effect of SCP production is less on environmental factors as compared to the livestock farming industry, and it takes less land and water. It emits fewer greenhouse gases and works with waste, thus minimising pollution. SCP also aids in the savings of bio-diversity by reducing the necessity for agricultural bases. It also makes SCP a better option for protein production compared to other means of protein production.

5. What is Single Cell Protein and explain its importance in diet?

SCP is rich in protein (50-80%) and is a good source of all the essential amino acids; thus, it is a complete protein, including all the dispersed amino acids in the natural protein. It also provides vitamins and minerals, thus increasing the nutritional value of the food. The digestibility of the commercial poultry feed SCP makes it possible to absorb all the nutrients without waste.

In human diets, it can replace missing nutrients in our diets, and for animals in feed, it boosts growth and production. SCP also encourages the safeguarding of long-term food security because it does not depend solely on traditional sources of proteins.

6. How does the nutritional value of Single Cell Protein compare to conventional protein sources?

Single Cell Protein generally has a high protein content (about 60-82% of dry weight) and contains all essential amino acids. It's also rich in vitamins and minerals. However, the exact nutritional profile varies depending on the microorganism and substrate used. Compared to conventional sources, SCP can be nutritionally comparable or superior in some aspects.

7. What are the potential health benefits of consuming Single Cell Protein?

Potential health benefits of consuming Single Cell Protein include high protein content, low fat content, presence of beneficial compounds like antioxidants and vitamins, and potential prebiotic effects. Some SCPs, like certain algae, also contain omega-3 fatty acids. However, the exact benefits depend on the specific microorganism and production method used.

8. How does the growth rate of microorganisms used in Single Cell Protein production compare to traditional protein sources?

Microorganisms used in Single Cell Protein production have significantly faster growth rates compared to traditional protein sources. For example, bacteria can double their biomass in a matter of hours, while it takes months or years for animals to reach maturity. This rapid growth allows for much faster protein production.

9. How does the amino acid profile of Single Cell Protein compare to that of animal proteins?

The amino acid profile of Single Cell Protein is generally comparable to that of animal proteins, containing all essential amino acids. However, the exact profile can vary depending on the microorganism used. Some SCPs may be limiting in certain amino acids (like methionine), which can be addressed through supplementation or genetic modification of the microorganism.

10. How does the water footprint of Single Cell Protein production compare to that of traditional livestock farming?

The water footprint of Single Cell Protein production is generally much lower than that of traditional livestock farming. While exact figures vary, SCP production typically requires only a fraction of the water needed to produce an equivalent amount of animal protein, making it a more water-efficient protein source.

11. What are the potential applications of Single Cell Protein beyond human food?

Beyond human food, Single Cell Protein has potential applications in animal feed, aquaculture, and as a protein supplement in various food products. It can also be used in the production of biofuels and as a source of specific nutrients or compounds in the pharmaceutical industry.

12. What are the potential applications of Single Cell Protein in addressing malnutrition in developing countries?

Single Cell Protein has potential applications in addressing malnutrition in developing countries due to its high protein content, rapid production, and ability to be produced locally with minimal resources. It could provide a sustainable protein source in areas with limited agricultural capacity or during food crises.

13. What are the potential applications of Single Cell Protein in the pet food industry?

Single Cell Protein has potential applications in the pet food industry as a sustainable and nutritious protein source. It can replace traditional animal proteins, reducing the environmental impact of pet food production. Some SCPs also offer additional benefits like improved digestibility or the presence of beneficial compounds that can enhance pet health.

14. What are the potential applications of Single Cell Protein in space exploration?

Single Cell Protein has potential applications in space exploration as a sustainable food source for long-term missions. Its rapid production, small space requirement, and ability to recycle waste make it an attractive option for closed-loop life support systems in space habitats or during interplanetary travel.

15. How does the use of genetic engineering in Single Cell Protein production compare to its use in traditional crop improvement?

Genetic engineering in Single Cell Protein production can potentially yield results more quickly than in traditional crop improvement due to the microorganisms' simpler genetics and faster generation times. It can be used to enhance protein content, improve amino acid profiles, or enable the use of new substrates, often with more precise and predictable outcomes than in complex plant genomes.

16. How does the cost of producing Single Cell Protein compare to traditional protein sources?

The cost of producing Single Cell Protein can vary widely depending on the microorganism, substrate, and production method used. In some cases, it can be more cost-effective than traditional protein sources, especially when utilizing waste products as substrates. However, large-scale production and consumer acceptance remain challenges in making it economically competitive.

17. What are the main challenges in the widespread adoption of Single Cell Protein?

The main challenges in widespread adoption of Single Cell Protein include scaling up production, reducing costs, improving taste and texture, ensuring consistent quality, addressing potential allergenicity concerns, and overcoming consumer skepticism about eating "microbial protein."

18. What role does genetic engineering play in Single Cell Protein production?

Genetic engineering can enhance Single Cell Protein production by improving the microorganisms' growth rates, increasing their protein content, enhancing their nutritional profile, or enabling them to utilize different substrates more efficiently. It can also be used to reduce potential allergens or improve the taste and texture of the final product.

19. Why is Single Cell Protein considered a potential solution to global food shortages?

Single Cell Protein is considered a potential solution to global food shortages because it can be produced quickly, requires minimal land use, and can utilize various waste products as growth substrates. It offers a sustainable and efficient way to produce protein-rich food, especially in areas with limited agricultural resources.

20. How does the production of Single Cell Protein impact the environment?

Single Cell Protein production generally has a lower environmental impact compared to traditional protein sources. It requires less land, water, and energy, and can utilize waste products as substrates. However, the exact environmental impact depends on the production method and energy sources used.

21. How does the protein yield per hectare compare between Single Cell Protein and traditional crops?

Single Cell Protein production typically has a much higher protein yield per hectare compared to traditional crops. While exact figures vary, SCP can produce several hundred times more protein per unit area than soy or other high-protein crops, making it a highly land-efficient protein source.

22. How does the production of Single Cell Protein impact biodiversity compared to traditional agriculture?

Single Cell Protein production generally has a lower impact on biodiversity compared to traditional agriculture. It requires less land, reducing habitat destruction, and doesn't contribute to issues like overfishing when used as an alternative to fish meal. However, the exact impact depends on the production method and energy sources used.

23. How does the digestibility of Single Cell Protein compare to traditional protein sources?

The digestibility of Single Cell Protein can vary depending on the microorganism and processing method used. Generally, bacterial proteins are less digestible than fungal or algal proteins due to their cell wall structure. However, proper processing techniques can improve digestibility, making some SCPs comparable to traditional protein sources in terms of digestibility.

24. How does the carbon footprint of Single Cell Protein compare to that of animal-based proteins?

The carbon footprint of Single Cell Protein is generally much lower than that of animal-based proteins. SCP production emits fewer greenhouse gases, requires less land (reducing deforestation), and can even utilize carbon dioxide as a substrate in some cases, potentially acting as a carbon sink.

25. How does the amino acid supplementation in Single Cell Protein compare to that in plant-based proteins?

Like some plant-based proteins, certain Single Cell Proteins may require amino acid supplementation to achieve a balanced nutritional profile. The specific amino acids needed depend on the microorganism used. However, many SCPs have a more complete amino acid profile than plant proteins, potentially requiring less supplementation.

26. How does the production of Single Cell Protein differ from traditional protein sources?

Unlike traditional protein sources like livestock or crops, Single Cell Protein is produced by cultivating microorganisms in controlled environments. This process is faster, requires less space, and can be less resource-intensive than raising animals or growing crops for protein.

27. What are the main types of microorganisms used in Single Cell Protein production?

The main types of microorganisms used in Single Cell Protein production are bacteria (e.g., Methylophilus methylotrophus), fungi (e.g., Fusarium graminearum), algae (e.g., Spirulina), and yeasts (e.g., Saccharomyces cerevisiae). Each type has unique characteristics and growth requirements.

28. What are the main substrates used for growing Single Cell Protein?

Common substrates for Single Cell Protein production include agricultural waste (like straw or molasses), industrial by-products (such as whey from cheese production), hydrocarbons (like methane or methanol), and even carbon dioxide. The choice of substrate depends on the microorganism and the desired end product.

29. What is the role of bioreactors in Single Cell Protein production?

Bioreactors play a crucial role in Single Cell Protein production by providing a controlled environment for microorganism growth. They allow for precise control of parameters like temperature, pH, oxygen levels, and nutrient supply, optimizing growth conditions and ensuring consistent product quality.

30. How does the concept of circular economy apply to Single Cell Protein production?

The concept of circular economy applies well to Single Cell Protein production as it can utilize waste products or by-products from other industries as growth substrates. This creates a closed-loop system where waste is transformed into valuable protein, reducing overall resource consumption and waste generation.

31. What are the main differences between prokaryotic and eukaryotic microorganisms used in Single Cell Protein production?

The main differences between prokaryotic (bacteria) and eukaryotic (fungi, algae, yeast) microorganisms in SCP production include cell structure, growth rates, and nutritional profiles. Prokaryotes generally grow faster but may have higher nucleic acid content, while eukaryotes often have a more favorable amino acid profile and lower nucleic acid content.

32. What are the main differences between autotrophic and heterotrophic microorganisms in Single Cell Protein production?

Autotrophic microorganisms (like some algae) can produce their own food using light or inorganic compounds, while heterotrophic microorganisms (like most bacteria and fungi) require organic carbon sources. Autotrophs are more sustainable as they can use CO2 as a carbon source, but heterotrophs generally have faster growth rates and can utilize a wider range of substrates.

33. What role does fermentation play in Single Cell Protein production?

Fermentation is a key process in Single Cell Protein production, especially for bacteria and yeast. It involves the controlled growth of microorganisms in a nutrient-rich medium, often in the absence of oxygen (for anaerobic organisms). The fermentation process allows for rapid biomass production and can be optimized for maximum protein yield.

34. How does the production of Single Cell Protein impact soil health compared to traditional agriculture?

Single Cell Protein production generally has a lower impact on soil health compared to traditional agriculture. It doesn't require arable land, reducing issues like soil erosion, nutrient depletion, and chemical runoff associated with crop farming. However, the production of substrates for SCP growth could still have indirect impacts on soil, depending on their source.

35. What are the potential applications of Single Cell Protein in the production of functional foods or nutraceuticals?

Single Cell Protein has potential applications in functional foods and nutraceuticals due to its high protein content and the presence of beneficial compounds like vitamins, minerals, and antioxidants. Some SCPs, particularly from algae, can be sources of compounds like omega-3 fatty acids or specific phytonutrients, making them valuable ingredients in health-promoting food products.

36. What is Single Cell Protein (SCP)?

Single Cell Protein (SCP) refers to protein derived from single-celled microorganisms like bacteria, fungi, algae, or yeasts. These microorganisms are grown rapidly on various substrates and harvested for their high protein content, which can be used as a food source for humans or animals.

37. How does the protein quality (in terms of biological value) of Single Cell Protein compare to that of eggs or milk?

The protein quality or biological value of Single Cell Protein can be high, but it varies depending on the microorganism used. Some SCPs, particularly from certain algae or fungi, can have a biological value comparable to eggs or milk. However, others may have a lower biological value due to limiting amino acids or reduced digestibility, which can often be addressed through processing or supplementation.

38. What are the main differences between using prokaryotic and eukaryotic microorganisms in terms of nucleic acid content in Single Cell Protein?

Prokaryotic microorganisms (bacteria) generally have a higher nucleic acid content compared to eukaryotic microorganisms (fungi, algae, yeast) used in Single Cell Protein production. High nucleic acid content can be a concern as it can lead to elevated uric acid levels in consumers. Eukaryotic SCPs often require less processing to reduce nucleic acid content, making them potentially more suitable for human consumption.

39. What are the potential risks or safety concerns associated with Single Cell Protein consumption?

Potential risks or safety concerns associated with Single Cell Protein consumption include possible allergenicity, presence of nucleic acids, potential contamination during production, and unknown long-term effects of consuming large amounts of microbial biomass. Rigorous safety assessments and quality control measures are necessary to address these concerns.

40. How does the scalability of Single Cell Protein production compare to traditional protein sources?

Single Cell Protein production is generally more scalable than traditional protein sources. It can be rapidly scaled up by increasing bioreactor size or number, doesn't require large land areas, and is less dependent on climate and geographical factors. However, challenges in large-scale production and processing still need to be addressed for full commercial scalability.

41. What are the main differences between batch and continuous fermentation in Single Cell Protein production?

Batch fermentation involves growing microorganisms in a fixed volume of medium until nutrients are depleted, while continuous fermentation involves constantly adding fresh medium and removing product. Continuous fermentation can provide higher productivity and more consistent product quality but requires more complex equipment and control systems.

42. How does the production of Single Cell Protein impact antibiotic resistance compared to livestock farming?

Single Cell Protein production generally has a lower impact on antibiotic resistance compared to livestock farming. While some antibiotics may be used to maintain sterile conditions in bioreactors, the overall use is much less than in animal agriculture. This reduced antibiotic use can help mitigate the development and spread of antibiotic-resistant bacteria.

43. What role do enzymes play in the processing and digestibility of Single Cell Protein?

Enzymes play a crucial role in processing Single Cell Protein and improving its digestibility. They can be used to break down cell walls, reduce nucleic acid content, and modify protein structures. This enzymatic treatment can enhance the nutritional value, digestibility, and sensory properties of the final SCP product.

44. What are the potential applications of Single Cell Protein in the production of meat alternatives?

Single Cell Protein has significant potential in the production of meat alternatives. It can be used as a base ingredient in plant-based meats, providing high protein content and a complete amino acid profile. Some companies are also exploring the use of SCP to create cultured meat products, offering a more sustainable alternative to traditional meat production.

45. What are the main challenges in optimizing the taste and texture of Single Cell Protein for human consumption?

The main challenges in optimizing taste and texture of Single Cell Protein for human consumption include masking potential off-flavors (like earthiness or bitterness), improving mouthfeel, and creating textures that mimic familiar protein sources. This often involves post-production processing, flavor addition, and innovative food technology applications.

46. How does the use of artificial intelligence and machine learning contribute to Single Cell Protein production?

Artificial intelligence and machine learning can contribute to Single Cell Protein production by optimizing growth conditions, predicting yields, identifying ideal substrates, and improving quality control. These technologies can analyze vast amounts of data to fine-tune production parameters, potentially leading to more efficient and cost-effective SCP production.

47. How does the regulatory landscape for Single Cell Protein differ around the world?

The regulatory landscape for Single Cell Protein varies significantly around the world. Some countries have established clear guidelines for SCP approval and use, while others are still developing regulations. In general, SCPs are subject to food safety regulations and may require specific approvals as novel foods. The regulatory process can be a significant factor in the commercialization of SCP products.

48. How does the concept of biorefinery apply to Single Cell Protein production?

The concept of biorefinery applies to Single Cell Protein production by maximizing the utilization of biomass components. In a biorefinery approach, not only is the protein extracted, but other valuable components like lipids, carbohydrates, and specific bioactive compounds are also isolated and used. This integrated approach improves the economic viability and sustainability of SCP production.

49. What role does metabolic engineering play in improving Single Cell Protein production?

Metabolic engineering plays a crucial role in improving Single Cell Protein production by optimizing the microorganisms' metabolic pathways. This can lead to increased protein yield, improved amino acid profiles, enhanced substrate utilization efficiency, or the production of specific valuable compounds alongside the protein. It allows for the creation of "designer" microorganisms tailored for optimal SCP production.

50. How does the use of Single Cell Protein in aquaculture compare to traditional fish meal?

Single Cell Protein can