Single cell protein (SCP) refers to the protein content of dead, dried microorganisms like yeast, fungi, bacteria and algae. These microorganisms are grown using various carbon sources and their protein is used as a supplement for animal feed and potentially human food. SCP is produced through fermentation processes using these microorganisms, with the protein then harvested, dried and processed. SCP provides an alternative protein source that can be produced sustainably using waste materials as feedstock. Key microorganisms used include yeast, fungi, algae and bacteria. While SCP shows promise as a sustainable protein source, further research is needed to optimize production methods and ensure safety for human consumption.

1. Single Cell Protein (SCP)
SURYA S
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2. Introduction
 Single cell protein (SCP) refers to dead, dry cells of microorganisms, such as
yeast, fungi, bacteria and algae
 These microorganisms grow on various carbon sources for their protein content
 The term, ‘single cell protein was firstly used by Carol Wilson in 1967 by replacing
the less aesthetic terminology, “petro protein”, “microbial protein.
 The majority of microorganisms used are unicellular, the protein content from
them is called , ‘single cell protein because of its superior nutritional quality in
terms of protein content and a very good supplement for animal feed.
 SCP do contain contents, such as vitamins, fats and minerals etc.
 Protein shortage in the Third World nations prompted in the cultivation of SCP on
large scale which resulted in the development of SCP technology for livestock and
human consumption

3.  It is estimated that SCP fermenters covering one third of a square mile can provide
10% of the World's protein requirement
 Saccharomyces cerevisiae is very promising and cost effective source of single cell
protein due to its bigger size, easy harvesting, lower amount of nucleic acids and good
blend of essential amino acids.
 Its protein quality & chemical score is comparable with soybean or egg protein.
 Single Cell Protein (SCP) sources that can be derived from algae, yeasts, fungi and
bacteria can be used as food supplements for animals or humans.
 Most targeted areas of SCP would apply towards animal feed .
 Single Cell Protein (SCPs) sources such as mycoproteins can serve as food substitutes
such as meat replacement products similar to Tofu
 QuornTM similar to Tofu, is used as a flexible meat substitute produce that has been
marketed as products such as chicken pieces, turkey and beef substitute products.

5. SCP Production Process
Following basic steps are involved in SCP production process.
 Selection of suitable strain of micro organisms
 Preparation of suitable medium with suitable carbon source.
 Fermentation
 Harvesting
 Post harvesting treatment, drying
 SCP processing for food

7. Production of SCP
 Production of SCP from hydrocarbons or waste of petroleum industry, from wood,
sewage, natural gas
SCP FROM WOOD:
 Cellulose from natural sources and waste wood is an attractive starting material for
SCP production because of its abundance.
 The association of cellulose with lignin in wood makes it intractable to microbial
degradation. Thermal or chemical pre treatment, used in combination with enzymatic
hydrolysis, is usually required.
SCP FROM CARBOHYDRATES:
 Whole milk whey or deproteinised whey is a carbohydrate source, which creates
disposal problems.
 While most organisms do not grow on lactose as a carbon source, strains of the
yeast Kluyveromyces marxianus readily grow on lactose.

8. SCP FROM NATURAL GAS
 Methane was initially considered as a SCP raw material because, as a
gas product, purification problems after fermentation would be
minimal.
Disadvantages associated with methane-based
processes are related to:
(a) The greater oxygen requirements necessary to fully oxidize methane
compared with paraffin’s,
(b) The low solubility of methane in water and
(c) the requirement that the fermentation plant is flame proof as
methane-oxygen mixtures are highly explosive.

9. Cultivation methods
 The production of single cell protein takes place in fermentation. This is
done by selected strains of microorganisms which are multiplied on suitable
raw materials in technical cultivation process directed to the growth of the
culture and the cell mass followed by separation processes.
 The process begins with microbial screening, in which suitable production
strains are obtained from samples of soil, water, air or from swabs of
inorganic or biological materials and are subsequently optimized by selection,
mutation, or other genetic methods.
 Then the technical conditions of cultivation for the optimized strains are
done and all metabolic pathways and cell structures will be determined.

10. Submerged fermentation
 In submerged process, the substrate used for fermentation is always in
liquid state which contains the nutrients needed for growth. The
fermentor which contains the substrate is operated continuously and the
product biomass is continuously harvested from the fermentor by using
different techniques then the product is filtered or centrifuged and then
dried.
 Aeration is an important operation in the cultivation, heat is generated
during cultivation and it is removed by using a cooling device. The
microbial biomass can be harvested by various methods. Single cell
organisms like yeast and bacteria are recovered by centrifugation while
filamentous fungi are recovered by filtration. It is important to recover
as much water as possible prior to final drying done under clean and
hygienic conditions.

11. Semisolid fermentation
 In semisolid fermentation, the preparation of the substrate is not
cleared and it is also more used in solid state e.g. cassava waste.
Submerged culture fermentations require more capital investment and
have high operating cost.
 The cultivation involves many operations which include stirring and
mixing of a multiphase system, transport of oxygen from the gas
bubbles through the liquid phase to the microorganisms and the
process of heat transfers from liquid phase to the surroundings. A
special bioreactor is designed for identifying mass and energy
transportation phenomena, called U-loop fermentor

12. Solid state fermentation
This process consists of depositing a solid culture substrate,
such as rice or wheat bran, on flatbeds after seeding it with
microorganisms; the substrate is then left in a temperature-
controlled room for several days.
Liquid state fermentation
Liquid state fermentation is performed in tanks, which can reach
1,001 to 2,500 square metres at an industrial scale. Liquid culture is
ideal for the growing of unicellular organisms such as bacteria or
yeasts. To achieve liquid aerobic fermentation, itis necessary to
constantly supply the microorganism with oxygen, which is generally
done via stirring the fermentation media.

13. Yeasts and Fungi
 Filamentous Fungi used for SCP production are: Chaetomium celluloliticum,
Fusarium graminearum, Paecilomyces varioti which grows on cellulose waste, starch,
and sulphite waste liquor respectively and content about 50 – 55 % protein .
 SCP is produced from yeasts viz. Candida utilis, Candida lipolytica, Saccharomyces
cerevisiae.
 Torula yeast (which grows on Ethanol) as a food is obtained through fermentation
using molasses as substrate and it has high protein–carbohydrate ratio than
forages.
 It is rich in lysine but poor in methionine and cysteine.
 Saccharomyces consists of high protein with good balance of amino acids and rich
in B–complex vitamins.
 It is more suitable as poultry feed. Yeast are higher in lysine content.
 Strict aseptic conditions are required when using Yeast as a SCP production.

14. Bacteria
 They have more than 80% protein but are poor in sulphur containing
amino acids. Brevibacterium uses hydrocarbons while Methylophilus
methylitropous uses methanol as a substrate.
Disadvantages:
 It has high nucleic acid content.
 Recovering the cells is a bit problematic.
 Endotoxin production should be carefully tested.

15. Algae
 Chlorella, Scenedesmus acutus and Spirulina maxima are grown for SCP.
 These have about 60% protein with good amino acid composition but less in
sulphur containing amino acids.
 Chlorella and Spirulina are used for commercial scale production in Taiwan,
Thailand, Japan, Israel, Mexico and USA.
 It is spray dried and sold as pills and powders.
Disadvantages:
 As they are rich in Chlorophyll, it is not advised for human consumption (except
Spirulina).
 It has low density i.e. 1-2 gm dry weight/litre of substrate.
 There is lot of risk of contamination during growth.

16. Spirulina
 The United Nations Organization (UNO) in its World Food Conference
of 1974 declared Spirulina as the best food for tomorrow.
 World Health Organization (WHO) has hailed Spirulina the greatest
super food on the earth.
 Upon testing it NASA scientists found 1 kg of Spirulina nutritionally
equal to 1000 kgs of assorted vegetables

17. Production Cost
 The production cost strongly influenced by the nature of raw starting
material used.
 If starting material used is disposed of as a waste product , then the
raw material cost is negative.
 However, if a useful material is used, then starting Material used will
play a major role in the final cost of SCP.
 Price of SCP varies depending on how it is used, i.e: SCP for human is
about 10 times more expensive than SCP for animal feed because it is
more highly refined

18. Uses of SCP
 provides instant energy
 it is extremely good for healthy eyes and skin
 provides the best protein supplemented food for under nourished
children serves as a good source of vitamins, amino acids, minerals,
etc.
 Used in therapeutic and natural medicines for controlling obesity,
lowers blood sugar level in diabetic patients, reducing body weight,
cholesterol and stress
 Used in Cosmetics products for maintaining healthy hair, production of
different herbal beauty products, like – Biolipstics, herbal face cream
etc.
 Used in Poultry and dairy farms as it serves as an excellent and
convenient source of proteins and other nutrients, it is widely used for
feeding cattle, birds, fishes, etc.

19. Advantages of Production
 It has high protein and low fat content.
 It is good source of vitamins particularly B-complex. e.g. Yeasts.
 It can be produced through-out the year.
 Waste materials are used as substrate for the production of these proteins. It reduces the
environmental pollution and helps in recycling of materials.
 SCP organisms grow faster and produce large quantities of SCP from relatively small area of
land and time.
 These have proteins with required amino acids that can be easily selected by genetic
engineering.
 During the production of SCP biomass, some organisms produce useful by products such as
organic acids and fats.
 It can be genetically controlled.
 It causes less pollution.
 Algal culture can be done in space which is normally unused.

20. SCP's Evaluation and Future Prospects
 SCP has a proven record as a source of protein which may be obtained with
large productivities in compact installations .
 new view is that there is a market for products of microbial origin, aimed
at animal and direct human consumption as substitutes for meat or even
fish, given the increasing depletion of fish stocks.
 Aside from this view, the problem of increasing world population and
limited food production may not demand SCP production at this time, but
remains as a latent issue.
 The continued research on the production of microorganisms for animal
and human consumption will undoubtedly find application in the future.
 This research should also incorporate the development of recombinant
strains from no conventional GRAS (Generally Regarded as a Safe) yeasts
and fungi .

21. Thank you …