ABOUT AUTHOR:
Rajesh G. Dobariya
shree M.&N. Virani Science College,
Rajkot
drajesh47@gmail.com
ABSTRACT
Single cell protein typically refers to source of mixed protein extracted from pure or mixed culture of algae, yeast, fungi or bacteria. The microbes which are used for single cell protein production must be non-pathogenic to plants, animals and man. Good nutritional value, easily and cheaply produced on scale, toxin free, fast growing, easily to separate from the medium and to dry. They have many silent feature. Biomass production is ordinarily carried out in continuous mode to maximize yields and economic scale. The raw material of this process is very cheap because we used molasses, whey, gas, oil etc. For a substrate. So SCP is waste to best. The molasses and various salts including ammonium and phosphate salt contain of the baker’s yeast. The yeast are used for the production of SCP. The baker’s yeast is useful to as and they create disadvantages also the SCP and baker’s yeast very useful for organism.
REFERENCE ID: PHARMATUTOR-ART-1885
INTRODUCTION
Single cell protein(SCP) typically refers to sources of mixed protein extracted from pure or mixed cultures of algae, yeasts, fungi or bacteria (grown on agricultural wastes) used as a substitute for protein-rich foods, in human and animal feeds.
EARLY HISTORY
Since 2500 BC yeasts have been used in bread and beverage production. In 1781 processes for preparing highly concentrated forms of yeast were established [1].
In 1919 Endomyces vernalis yielded fats from sulphite liquor (frompaper manufacture), and similarly in 1941 employing Geotrichum.[1]
"Food from oil"
In the 1960s, researchers at British Petroleum developed what they called "proteins-from-oil process": a technology for producing single cell protein by yeast fed by waxy n-paraffins, a product produced by oil refineries. Initial research work was done by Alfred Champagnat at BP's Lavera Oil Refinery in France; a small pilot plant there started operations in March in 1963, and the same construction of the second pilot plant, at Grangemouth Oil Refinery in Britain, was authorized.[2]
The term SCP was coined in 1966 by Carol L. Wilson at MIT [3][4]
The "food from oil" idea became quite popular by the 1970s, with Champagnat being awarded the UNESCO Science Prize in 1976,[5] and paraffin-fed yeast facilities being built in a number of countries. The primary use of the product was as poultry and cattle feed.[6]
The Soviets were particularly enthusiastic, opening large "BVK" (belkovo-vitaminny kontsentrat, i.e., "protein-vitamin concentrate") plants next to their oil refineries in Kstovo (1973) [7][8][9]and Kirishi (1974).[10] The Soviet Ministry of Microbiological Industry had eight plants of this kind by 1989, when, pressured by the environmentalist movements, the government decided to close them down, or convert to some other microbiological processes.[10]
SCP PRODUCTION PROCESS
Single cell proteins develop when microbes ferment waste materials (including wood, straw, cannery and food processing wastes, residues from alcohol production, hydrocarbons, or human and animal excreta. The problem with extracting single cell proteins from the wastes is the dilution and cost. They are found in very low concentrations, usually less than 5%. Engineers have developed ways to increase the concentrations including centrifugation, flotation, precipitation, coagulation and filtration, or the use of semi-permeable membranes.
The single cell protein needs to be dehydrated to approximately 10% moisture content and/or acidified to aid in storage and prevent spoilage. The methods to increase the concentrations to adequate levels, and de-watering process require equipment that is expensive and not always suitable for small-scale operations. It is economically prudent to feed the product locally and shortly after it is produced.
Microbes
Microbes employed include yeasts (Saccharomyces cerevisiae, Candida utilis=Torulopsis and Geotrichum candidum (=Oidium lactis)), other fungi (Aspergillus oryzae, Sclerotium rolfsii, Polyporus and Trichoderma), bacteria (Rhodopseudomonas capsulata, and algae (Chlorella and Spirulina[1] ). Typical yields of 43 to 56%, with protein contents of 44 to 60%.
The fungus Scytalidium acidophilum grows at below pH 1, offering advantages of (i) low-cost aseptic conditions, (ii) avoiding over 100-fold dilution of the acidic hydrolysates to pH values needed for other microbes, and (iii) after the biomass is harvested, the acids can be reused.
Commercial production of SCP (Spirulina) includes Cyanotech in Hawaii and Earthrise in California.
Product Safety and Quality
Some contaminants can produce mycotoxins. Some bacterial SCP have amino acid profiles different from animal proteins. Yeast and fungal proteins tend to be deficient in methionine.
Microbial biomass has a high nucleic acid content,and levels need to be limited in the diets of monogastric animals to <50g per day. Ingestion of purine compounds arising from RNA breakdown, leads to increased plasma levels of uric acid, which can cause gout and kidney stones. Uric acid can be converted to allantoin, which is excreted in urine. Nucleic acid removal is not necessary from animal feeds but is from human foods.
Composition of Single Cell Proteins
–Yeast single-cell protein (SCP) is a high-nutrient feed substitute. This study evaluates the dual applications of a novel recombinant Pichia pastoris SMD1168H (SMD) yeast, expressing a tilapia vitellogenin protein (rVtg), as an SCP diet for Artemia and the first-feeding fish larvae. Instar II Artemia fed rVtg, rVtg precultured in 5% fish oil (rVtg-FO), Saccharomyces cerevisiae (SC), or native SMD had greater lipid contents (P < 0.05) than the freshly hatched. Lipid deposition in the Artemia fed rVtg or rVtg-FO was greater (P < 0.05) than in those fed SMD or SC. Diet-induced accumulation of low levels of docosahexaenoic acid [22:6(n-3)] was detected only in Artemia fed the rVtg-based diets. Tilapia (Oreochromis mossambicus) larvae were fed solely yeast diets singly or in combination (d 3–22), or a staggered regimen of yeast (d 3–12) followed by unenriched or yeast-enriched Artemia (d 13–22). The larvae fed rVtg for 22 d increased in length and weight (P < 0.05), whereas those fed SC or SMD suffered growth suppression and high mortality. Such adverse consequences were ameliorated when 50% of SC was substituted with rVtg. The larvae prefed rVtg followed by a dietary switch to Artemia preenriched for 48 h with rVtg or rVtg-FO were greatest in length, had the highest weight gain, and lived the longest. Besides delivering rVtg protein, essential fatty acids and amino acids, rVtg may have probiotic effects in enhancing larval survival.
ADVANTAGES OF SCP
- hold at 64C inactivates fungal proteases and allows RNases to hydrolyse RNA with release of nucleotides from cell to culture broth
- Large-scale production of microbial biomass has many advantages over the traditional methods for producing proteins for food or feed.
- Microorganisms have a high rate of multiplication to hence rapid succession of generation (algae: 2-6 hours, yeast: 1-3 hours, bacteria: 0.5-2 hours)
- They can be easily genetically modified for varying the amino acid composition.
- A very high protein content 43-85 % in the dry mass.
- They can utilize a broad spectrum of raw materials as carbon sources, which include even waste products. Thus they help in the removal of pollutants also.
- Strains with high yield and good composition can be selected or produce relatively easily.
- Microbial biomass production occurs in continuous cultures and the quality is consistent since the growth is independent of seasonal and climatic variations.
- Land requirements is low and is ecologically beneficial.
- A high solar energy conversion efficiency per unit area.
- Solar energy conversion efficiency can be maximized and yield can be enhanced by easy regulation of physical and nutritional factors.
- Algal culture can be done in space which is normally unused and so there is no need to compete for land.
NOW YOU CAN ALSO PUBLISH YOUR ARTICLE ONLINE.
SUBMIT YOUR ARTICLE/PROJECT AT articles@pharmatutor.org
Subscribe to Pharmatutor Alerts by Email
FIND OUT MORE ARTICLES AT OUR DATABASE
Central Food Technology Research Institute, Mysore is conducting research on the use of Spirulina as a food and feed supplement.
It is cultured, dried, powdered and is used in the form of one gram tablets.
Composition of multin (i.e. dried powder of Spirulina fusiformis) constituents are in per 100 of powder).
When fishes and children are fed on Spirulina, encouraging results were obtained.
It is therefore hoped that Spirulina will in the immediate future become an important diet supplement of humans and also marine and fresh water life.
Single Cell Protein Process
Regardless of the type of substrate or organism employed, the production of SCP involves following basic steps:
(i) preparation of suitable medium with suitable carbon source;
(ii) prevention of contamination of medium and the plant;
(iii) production of the desired micro organism;
(iv) separation of microbial biomass and its processing.
The medium for SCP production varies according to the micro organism. Among other things, the medium must contain a carbon source for cultivating the heterotrophic micro organisms, although green algae (Chlorella, Scenedesmus, Spirulina, etc.) can be cultivated autographically without a dissolved carbon source.
Single Cell Protein –
SCP - SCP is the name given to a variety of microbial products, that are produced by fermentation. When properly produced, this materials make satisfactory proteinaceous ingredients for animal feed or human food. The production of protein from hydrocarbon wastes of the petroleum industry is the most recent microbiological industry.
Yeast, fungi, bacteria, and algae are grown on hydrocarbon wastes, and cells are harvested as sources of protein. It has been calculated that 100 lbs of yeast will produce 250 tons of proteins in 24 hours, whereas a 1000 lbs steer will synthesize only 1 lb of protein 24 hours and this after consuming 12 to 20 lbs of plant proteins. Similar, algae grown in ponds can produce 20 tons (dry weight) of protein, per acre, per year.
This yield is 10 to 15 times higher than soybean and 25 to 50 times higher than corn. There are both advantages and disadvantages in using microorganisms for animal or human consumption. Bacteria are usually high in protein (50 to 80 percent) and have a rapid growth rate. The principal disadvantages are as follows:
1. Bacterial cells have small size and low density, which makes harvesting from the fermented medium difficult and costly.
2. Bacterial cells have high nucleic acid content relative to yeast and fungi This can be detrimental to human beings, tending to increase the uric acid level in blood. This may cause uric acid poising or gout. To decrease the nucleic acid level additional processing step has to be introduced, and this increases the cost.
3. The general public thinking is that all bacteria are harmful and produce disease. An extensive education programme is1required to remove this misconception and to make the public accept bacterial protein.
Filamentous fungi have advantages .in ease of harvesting, but have their limitations in lower growth rates, lower protein content, and acceptability. Algae have disadvantages of having cellulosic cell walls which are not digested by human beings. Secondly, they also concentrate heavy metals.
Single cell protein basically comprises proteins, fats carbohydrates, ash ingredients, water, and other elements such as phosphorus and Potassium. The composition depends upon the organism and the substrate which it grows. some typical compositions which are compared with soymeal and fish meal. If SCP is to be used successfully, there are five main criteria to be satisfied;
1. The SCP must be safe to eat.
2. The nutritional value dependent on the amino acid composition must be high.
3. It must be acceptable to the general public.
4. It must have the functionality, i.e. characteristics, which are found in common staple foods.
5. The economic viability of the SCP process is extremely complex and is yet to be demonstrated
Baker's Yeast Production
The production of baker's yeast is the largest domestic use of a microorganism for food purposes. Baker's yeast is a strain of Saccha romyces cerevisiae. The strain of the yeast is carefully selected for its capacity to produce abundant gas quickly, its viability during ordinary storage, and its ability to produce desirable flavour.
The organisms are mixed with bread dough to bring about vigorous sugar fermentation. The carbon dioxide produced during the fermentation is responsible for leavening or rising of the dough
A pure culture of the selected strain of yeast is first grown in the laboratory and gradually built up to larger and larger volume by transfer from the test tube to the fermenter tank. Great care is taken to prevent contamination at any stage of development of the culture.
During manufacturing, the strain is inoculated into a medium which frequently contains molasses and corn steep liquor as sources of carbon, nitrogen, and mineral salts. The reaction of the medium is adjusted to pH 4.4 to 4.6.
The inoculated medium is incubated at a temperature of 25 to 26°C, and is aerated during the incubation period. Yeasts oxidize sugars under aerobic conditions with the liberation of energy. A large part of this energy is utilized for the synthesis of cell protoplasm. The yeast cells multiply rapidly and exhaust the sugar supply within 10 hours
At the end of incubation the yeast cells are removed from the fermented medium by centrifugation, washed and mixed with starch or corn meal, and then being pressed into cake form.
Yeast cakes must be kept cool to preserve the cells and to prevent spoilage by other micro organisms. They may also be dried. Dried yeast remains viable for several months. Yeasts are rich in vitamins and in most of the essential amino acids required by man and animals.
Biomass and Single Cell Protein
Microbial cells are produced for two main applications,
(a) as a source of protein for animal or human food, (Single Cell Protein) or (b) for use as a commercial inoculum in food fermentations and for agriculture and waste treatment.
As a commodity, SCP must be competitive with commercial animal and plant proteins, in terms of proce and nutritional value and must conform with human and animal food safety requirements. Productivity, yield and selling price are the major factors affecting the economics of SCP production.
Microbial inoculants, which are used as a process aid, generally have a higher value.
In this case, the objective of the production process is to optimize yield of viable cells of defined biological activity with good shelf life characteristics.
Saccharomyces cerevisiae, is categorised primarily as a microbial inoculant.
Inactive dried brewer's or baker's yeast is also used as a dietary source of vitamins and trace minerals in specific medical conditions.
Considerable amounts of yeast extract are produced from bakers yeast as a source of flavour and vitamins.
Single Cell Protein Production
Product Safety and Quality
SCP has applications in animal feed, human food and as functional protein concentrates.
Some bacterial SCP have amino acid profiles similar to animal/plant protein. Yeast, fungal and soya bean proteins tend to be deficient in methionine.
Ingestion of RNA from non-conventional sources should be limited to 50g per day. Ingestion of purine compounds arising from RNA breakdown, leads to increased plasma levels of uric acid, which can cause gout and kidney stones.
High content of nucleic acids causes no problems to animals since uric acid is converted to allantoin which is readily excreted in urine.
Nucleic acid removal is not necessary from animal feeds but is from human foods.
A temperature hold at 64C inactivates fungal proteases and allows RNA-ases to hydrolyse RNA with release of nucleotides from cell to culture broth.
A 30 min stand at 64C reduces intracellular RNA levels in Fusarium graminearum from 80mg/g to 2mg/g.
Production
Large scale fermenters are required High biomass productivity requires high oxygen transfer rates which promotes high respiration rates which in turn increase metabolic heat production an the need for an efficient cooling system.
In order to maximise fermentation productivity it is essential to operate continuous fermentation processes.
Different processes have adopted different fermenter designs with respect to process requirements.
NOW YOU CAN ALSO PUBLISH YOUR ARTICLE ONLINE.
SUBMIT YOUR ARTICLE/PROJECT AT articles@pharmatutor.org
Subscribe to Pharmatutor Alerts by Email
FIND OUT MORE ARTICLES AT OUR DATABASE
BP Process – Candida on n-paraffin
Mechanically agitated fully baffled fermenters with turbine mixers.
Reactor feed consists of paraffin, gaseous ammonia and other salts.
Oxygen requirements per unit biomass produced by aerobic micro-organisms grown on n-hexadecane is 2.5 times higher rhan that required for growth on glucose and amounts to 2.2 kg O2 per kg biomass.
Heat produced was 25000 kJ/kg biomass. Fermenters require substantial agitation.
Because of the insoluble nature of alkanes, they exist in agiteated fermenter as suspensions of alkane drops 1-100mm in diameter.
Cell recovery is by centrifugation, producing 15% dry solids, evaporation to 25% dry solids and spray drying.
ICI Process – Methylophilus methylotrophus from methanol.
Pressure recycle fermentor. A combination of an airlift and loop reactor consisting of an airlift column, a down-flow tube with heat removal and a gas-release space.
The nitrogen source is ammonia gas and pH is controlled between 6 and 7.
Cell specific growth rate is approximately 0.5h-1 and cell yield of 0.5 g/g.
Methanol is oxidised via dehydrogenation to formaldehyde which can either be assimilated for conversion to cell mass or further oxidised to CO2 with concomitant energy production.
Cells are recovered by agglomeration followed by centrifugation, flash dried and ground.
Bel Fromageries process: Kluyveromyces marxianus from whey.
Whey which contains about 5% lactose, 0.8% protein and 0.2-0.6% lactic acid, is used as a substrate.
Biomass production requires an aerobic fermentation whereas aeration is minimal for ethanol production.
For feed grade biomass, the entire fermentation contents, containing yeast, residual whey proteins, minerals and lactic acid may be recovered.
For preparation of food grade material, cells are harvested by centrifugation, washed and dried.
Cell yield is 0.45-0.55 g/g based on lactose consumed.
RHM Mycoprotein process: Fusarium graminearum from glucose.
Medium components include food grade glucose syrup, gaseous ammonia, salts, and biotin.
Fermentation pH is controlled at 6 by gaseous ammonia addition, fed into the air inlet stream.
Cell concentrations are 15-20g/L and a specific growth rate of up to 0.2h-1 is achieved. Following cyclone separation and an RNA reduction step, cells are recovered by rotary vacuum filtration and formulated into a range of producT
CONCLUSION
Singel cell protein easily to sythesized in industrial scale. Raw material of this process is very cheap because we used a molasses, whey,gels,oil, etc. For substrat. The baker’s yeast is useful to scp production and very useful organism.
REFRENCES
1. Jean Marx, ed. A Revolution in Biotechnology. Cambridge University Press. pp. 1–227.
2. Bamberg, J. H. (2000). British Petroleum and global oil, 1950-1975: the challenge of nationalism. Volume 3 of British Petroleum and Global Oil 1950-1975: The Challenge of Nationalism, J. H. Bamberg British Petroleum series. Cambridge University Press. pp. 426–428.
3. "Nutrition - Single Cell Protein, Twenty Years Later". biopolitics.gr/HTML/PUBS/VOL1/isreali.htm.
4. "UNESCO Science Prize: List of prize winners". UNESCO. 2001. unesco.org/science/psd/prizes/unesco/unesco_winners.shtml. Retrieved 2009-07-07.
5. National Research Council (U.S.). Board on Science and Technology for International Development (1983). Workshop on Single-Cell Protein: summary report, Jakarta, Indonesia, February 1-5, 1983. National Academy Press. p. 40.
6. Soviet Plant to Convert Oil to Protein for Feed; Use of Yeast Involved, By THEODORE SHABAD. the New York Times, November 10, 1973.
7. RusVinyl – Summary of Social Issues (EBRD)
8. Microbiological industry's first plant, in: Stanislav MarkovKstovo, Russia's Young City
9. Singh B D. Biotechnology. Kalyani publishers, New Dehli, India.
NOW YOU CAN ALSO PUBLISH YOUR ARTICLE ONLINE.
SUBMIT YOUR ARTICLE/PROJECT AT articles@pharmatutor.org
Subscribe to Pharmatutor Alerts by Email
FIND OUT MORE ARTICLES AT OUR DATABASE
.png)
