Single Cell Protein (SCP): Microbes, Production,
Uses
Single Cell Protein is the dried cells of microorganisms consumed as a
protein supplement by humans or animals.
The protein is derived from cells of micro-organisms such as yeast, fungi,
algae, and bacteria which are grown on various carbon sources for
synthesis.
SCPs contain vitamins, e.g., thiamine, riboflavin, pyridoxine, nicotinic acid,
pantothenic acid, folic acid, biotin, cyanocobalamin, ascorbic acid, β-
carotene and α- tocopherol; essential amino acids, represented by lysine
and methionine; minerals; nucleic acids and lipids.
The microorganisms used in single-cell protein production should have
the following properties.
1. Absence of pathogenicity and toxicity
2. Protein content and quality
3. Digestibility and organoleptic qualities
4. Growth rate
5. Adaptability to unusual environmental conditions such as pH,
temperature, and mineral concentrations.
6. Ability to utilize carbon and nitrogen sources.
History of Single Cell Protein (SCP)
The SCP was first developed during World War I.
In 1919, Sak in Denmark and Hay duck in Germany invented a method
named Zulaufverfahren in which sugar solution was fed to an aerated
suspension of yeast instead of adding yeast to the diluted sugar solution.
Saccharomyces cerevisiae was produced in Germany from molasses to
replace protein.
Candilaarborea and C. utilis were used during the Second World War.
Similarly, during World War II Candida utilis was used in soup and
sausage.
Many industries were established in the USA and Europe, especially for C.
utilis production after the war.
During the 1960s and 1970s, production industries were established in the
UK, France, Italy, Russia, Japan, and Taiwan.
The term single-cell protein was coined by Carol L. Wilson in 1966.
Organisms used as Single Cell Protein (SCP)
and the substrate used for their production
S.N
Microalgae Bacteria Fungi
.
They are phototrophic They can be divided into unicellular
1
organisms. yeast and mold.
Bacteria are potential SCP as they
They are potential SCP due to
possess high protein content (50- Yeasts are mainly
their chemical composition
80%) along with vitamins, used in aquaculture
which contains proteins, Mold is found
phospholipids, and other as it is the protein-
essential fatty acids mainly to be highly
2 functional molecules. They are rich ingredient in
omega-3 fatty acids, and digestible by
capable of growing on a wide aquafeeds, with
several bioactive compounds. fish.
range of substrates from crude protein
They have relatively low
carbohydrates to gaseous and contents of 38–52%.
nucleic acid content (3–8%).
liquid hydrocarbons
The advantages of
The advantages of using algae The advantages of using bacteria using yeasts include The advantages
include simple cultivation, are its use of a wide range of a high level of malic of using mold
3 effective utilization of solar substrates, their short time for acid content, can include high
energy, faster growth, and generation, production of vitamins grow in acidic pH nucleic content
high protein and and micronutrients. and is easy to of up to 10%.
harvest.
The potential disadvantage is
the economical limitations of
scale-up, digestibility (need The potential disadvantages are The potential disadvantages include
for cell wall disruption to palatability issues, high content of the possible presence of the toxin,
4
release nutrients), the large nucleic acid, and production of slower growth rate, and lesser content
surface area needed for toxins. of protein (45- 65%).
cultivation, and contamination
risk in an open pond.
Fungi and substrates utilized by them and the
protein content produced
S.N. Substrate Fungi
Aspergillus fumigatus,
1 Maltose, Glucose
Rhizopus chinensis
Aspergillus niger,
2 Cellulose, Hemicellulose A. oryzae,
Cephalosporium eichhorniae, Chaetomium cellulolyticum
3 Glucose, Lactose, Galactose Penicillium cyclopium
Bacteria and substrates utilized by them and the
protein content produced
S.N. Substrate Bacteria Protein conten
1 Orange wastes, lemon wastes Rhodococcus opacus
2 Commercial shrimp feed Afifella marina STW181 >46
Bacillus cereus 68
3 Ram horn Bacillus subtilis 71
Escherichia coli 66
4 Potato starch processing waste Bacillus licheniformis 38
Bacillus pumilis 46
Bacteria and substrates utilized by them and the
protein content produced
S.N. Substrate Bacteria Protein conten
1 Orange wastes, lemon wastes Rhodococcus opacus
2 Commercial shrimp feed Afifella marina STW181 >46
Bacillus cereus 68
3 Ram horn Bacillus subtilis 71
Escherichia coli 66
Bacillus licheniformis 38
4 Potato starch processing waste
Bacillus pumilis 46
Advantages of Single Cell Protein
Microorganisms are usually used for the production of SCP because of the
following advantages.
1. Microorganisms grow at a faster rate compared to the growth of protein-
rich grain which takes a year for production.
2. The quality and quantity of protein are better (60-80%).
3. A wide range of inexpensive raw materials can be used easily.
4. The production process is easy and simple.
5. The microorganisms can be easily subjected to genetic manipulation.
6. The microorganism can be produced all-around a year.
7. They can utilize a wide range of substrates.
8. The production of SCP is eco-friendly, cost-effective, and energy efficient.
Disadvantages of Single Cell Protein
1. The production of SCP is a complex process that requires strict control
over various environmental factors.
2. Maintaining the quality of SCP is a hard job as the harvesting and
purification after production of SCP production remains a problem.
3. SCP is not a suitable source of all the essential amino acids, so it is
typically used as a supplement to other protein sources
4. Despite the many potential benefits of SCP, consumer perception remains
a significant challenge, as many people may be skeptical of consuming a
product derived from microorganisms.
Applications of Single Cell Protein
In animal feed and nutrition, for the stuffing and fattening of poultry,
laying hens, calves, and pigs.
As food additives (vitamin and aroma carriers and emulsifying agents), to
enhance nutritional value (of baked food items, ready-made meals, soups,
etc.), and as starter cultures (baker’s, brewer’s, and wine yeast).
In industrial processes, as a foam-stabilizing agent, and in paper and
leather processing.
SCP provides the best protein-supplemented food for undernourished
children as it serves as a good source of vitamins, amino acids, minerals,
etc.
They are used in therapeutic and natural medicines for controlling
obesity, lowers the blood sugar level in diabetic patients, reduces body
weight, cholesterol, and stress, and prevents the accumulation of
cholesterol in the body.
SCP is used in Cosmetics products for maintaining healthy hair,
production of different herbal beauty products, like- Biolipstics, herbal
face cream, etc.
