Concept of Single Cell Protein (SCP)

Single Cell Protein (SCP)

Microbial biomass or proteins extracted therefrom obtained from processes in which bacteria, yeasts, other fungi or algae are cultivated in large quantities as human or animal protein supplement in animal feed or in human nutrition.Purified, dried microorganisms used as source of protein are called as single celled proteins. In olden days, the filamentous alga Spirulina was harvested in the lake Chad of Africa was consumed as food. During 1st world war Germans used Candida utilis in soups and sausages. It was extensively used during second world war. It was produced in industrial scale in 1967.

Advantages of SCP

• It has high protein and low fat content.

• It is good source of vitamins particularly B-complex. e.g. Mushrooms and 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 aminoacids that can be easily selected by genetic engineering.

• During the production of SCP biomass, some organisms produce useful bye products such as organic acids and fats.

Sources of SCP

1.  Algae:

• Chlorella, Scenedesmus acutus and Sprulina 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 Thaiwan, Thailand, Japan, Israel, Mexico

and USA.

• It is spray dried and sold as pills and powders.

• Spirulina grown on sewage water is free of pathogenic microorganisms.

Disadvantages:

• These are not suitable for human consumption because they are rich in Chlorophyll. (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.

2.  Yeasts and Fungi

• The filamentous fungi such as Chaetomium celluloliticum – grows on cellulose waste, Fusarium graminearum – grows on starch and Paecilomyces varioti – grows on sulphur liquar are used for the production of SCP. These have about 50 – 55 % protein.

• Yeasts such as Candida utilis (Torula yeast), Candida lipolytica – grow on Eathanol and Saccharomyces cervicea – grows on Molasses are used for SCP production.

• Torula yeast as a food is obtained through fermentation using molasses as substrate. 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.

• Several species of Mushrooms are used as protein rich food.

Disadvantages:

• These have high nucleic acid content.

• Filamentous fungi show slow growth rate than yeasts and bacteria.

• There is contamination risk.

• Some strains produce mycotoxins and hence they should be screened.

3.  Bacteria

• These have more than 80% protein. They are poor in sulphur containing amino acids.

• Brevibacterium uses hydrocarbons as substratum and Methylophilus methylitropous uses methanol.

• It has high nucleic acid content .

Disadvantages:

• It has high RNA content.

• Risk of contamination is very high during the production process.

• Recovering the cells is a bit problematic.

• Endotoxin production should be carefully tested.