Single Cell Protein (SCP) PDF - Biotechnology Textbook

Here's a structured markdown conversion of the provided text, formatted for better readability: # Single Cell Protein (SCP) and Mycoprotein (Page 415) ## C. Substrates Used for Production of SCP * A variety of substrates are used for SCP production. Availability of necessary substrates is of con...

Here's a structured markdown conversion of the provided text, formatted for better readability: # Single Cell Protein (SCP) and Mycoprotein (Page 415) ## C. Substrates Used for Production of SCP * A variety of substrates are used for SCP production. Availability of necessary substrates is of considerable biological and economic importance. * **Algae:** Contain chlorophylls, don't require organic wastes, use sunlight and carbon dioxide. * **Bacteria & Fungi:** (Except photoautotrophs) Require organic wastes as they don't contain chlorophylls (Roth, 1982). * **Major Substrate Components:** * Sugars (sugarcane, sugarbeet). * Starch (grains, tapioca, potato). * Lignocelluloses from woody plants. * Whey and refuses from processed food. * Aromatic compounds or hydrocarbons (Bull et al., 1983). * Renewable sources such as agricultural wastes or by-products are gaining importance due to petroleum price increases. (See Chapter 23). ## D. Nutritional Value of SCP * Considerable information is available on microbial cell composition (protein, amino acids, vitamins, minerals) (Litchfield, 1979). * Commercial value depends on nutritional performance, and it must be evaluated against prevalent feed protein. * SCPs (from alkanes or methanols) are characterized by good content and balance in essential amino acids (Senez, 1986). * Growth medium governs the protein and lipid content. Yeasts, moulds and higher fungi have higher cellular lipid content and lower nitrogen and protein contents, when grown in media having high amount of available carbon as energy source and low nitrogen (Litchfield, 1979). * Crude protein in dry matter: * Algae and yeasts (conventional substrates): 50-60%. * Alkane yeasts: 55-65%. * Bacteria: ~80%. * High nucleic acid-free protein is extremely important for economic efficiency. * High protein and fat contents are of prime importance; carbohydrates are not. * Crude ash content is determined by the nutrient salts of fermentation medium (Roth, 1982). * Crude protein estimation is based on total nitrogen multiplied by 6.25. This is somewhat erroneous as the value of nucleic acid is also included. * The most important measure of nutritional value is the actual performance of SCP products as determined in feeding studies. * Determinants of utility differ for humans and animals. for human beings: protein digestibility and protein efficiency ratio (PER), biological value or net protein utilization (NPU) are the parameters for food application for animals, metabolizable energy, protein digestibility and feed conversion ratio (weight of ration consumer/weight gain) are the measures or performance in broiler, chickens, swine and calves (and egg laying in hens) * **Digestibility (D):** Percentage of total nitrogen consumed that is absorbed. $D = \frac{Ni - Fn}{Ni}$ where: * Ni = nitrogen ingested from SCP * Fn = nitrogen content in faeces after feeding SCP * **Biological Value (BV):** Percentage of total nitrogen assimilated retained by the body, accounting for endogenous nitrogen loss via urine. $BV = \frac{Ni - (Fn + Un)}{(Ni - Fn)} \times 100$ where: * Un = nitrogen content in urine after feeding SCP * **Protein Efficiency:** Proportion of nitrogen retained when the test protein is compared to a reference protein (e.g., egg albumin) (Riviere, 1977). * Nutritional values are in Table 18.3, indicating good to very good protein digestibility for bacteria/yeasts on unconventional substrates (Roth, 1982). * There are problems that warrant against the use of SCP products: * High nucleic acid content (kidney stones, gout). * Potential toxic secondary metabolites. * Poor digestibility, gastrointestinal/skin reactions (Litchfield, 1979). ## E. Genetic Improvements in Microbial Cells (Page 416) * SCP production is in its infancy and needs boosting. * Genetic improvement is one way to enhance productivity/quality. * Sosa Texcoco, Mexico, is researching genetically engineered cells that grow in alkaline environments (pH 8.0-10.0). * Ciferri (1981) developed *S. platensis* mutants with 40x longer pools of certain amino acids. * Transfer/expression of beneficial genes has opened a new era for algal protein/compound production. * Rochaix and Van Dillerviger (1982) introduced genes of *S. cerevisiae* into *Chlamydomonas reinhardii*. ## F. Production of Algal Biomass * Algae (cyanobacteria and unicellular eukaryotes) grow autotrophically using sunlight/artificial light, carbon dioxide, and carbohydrates. * Cultivation occurs in large trenches, sewage oxidation ponds (Oswald, 1969) or artificial illumination systems (Litchfield, 1967). * *Chlorella* strains are used in biotechnology due to high protein content, improving protein deficiency and serving as feed. *The image shows an algal culture with small green circles filling the frame, and the following caption: Chlorella has multipurpose use in biotechnological applications.* * In many countries, strains of *Chlorella* are utilized for sewage oxidation and waste water treatment (Kessler, 1989). * For cultivation of algae on sewage wastes, oxidation ponds are prepared. For example, a mixed culture of *Chlorella ellipsoides* and *Scenedesmus obliguus* was developed in open pond systems in Japan. ### 1. Factors Affecting Biomass Production (Page 417) * Illumination time. * Light intensity. * CO2 supply: Concentrations vary, affecting growth. * Nitrogen sources: Ammonium salts/nitrates increase yield. * Agitation: To maintain cells in suspension. * Biomass yield: 12-15 g/m²/day (dry weight) for *Spirulina maxima* and *Scenedesmus quadricauda* (Clement, 1968). * Mass cultivation has started in many countries (Japan, Germany, Mexico, Czechoslovakia, India). * In India, NEERI (Nagpur) developed a technique for sewage oxidation pond systems. * CFTRI (Mysore) showed that microalgae like *Scenedesmus acutus* and *Spirulina platensis* can be cultivated and are comparable to conventional foods in nutrients. *Figure 18.1 shows a flow diagram of algae cultivation in sewage oxidation ponds, the diagram depicts the following flow*. Sewage goes through primary treatment which becomes Green algae which turn into green algae and BGA (NHC) or straight into BGA (HC) These happen in different culture ponds across stages one two three and four Nutrient recycling also takes place through Algal separation and recovery This goes into SCP (Feed) SCP (Food) and Aquaculture The Algal biomass becomes fertilizers or goes through Anerobic digestion **(Page 418)** ## 2. Harvesting the Algal Biomass * Harvesting is problematic due to settling and mixing. Cells are recovered by concentration, dewatering, and drying. * Flocculants (aluminum sulfate, calcium hydroxide, cationic polymers) are sometimes added. * Methods of separation include centrifugation, flocculation, but it is not always economically feasible. * Harvesting cyanobacteria (e.g., *Spirulina*) is easier because filaments float due to gas vacuoles. * Cells fix atmospheric nitrogen, are filtered, and dried with hot air. * Algal yield (stabilization pond): ~114 tonnes/ha/year. California: 70 tonnes/ha/year of *Scenedesmus* (sewage). Bangkok: 170 tonnes/ha/year (Vijayan, 1988). ## 3. SCP Product of *Spirulina* * 1821: Bernal Diaz del Castillo described 'tecuitlatl' biscuits containing dried *S. maxima*. * 1964: J. Leonard noticed blue-green biscuits (dihe) consumed by locals, consisting of *Spirulina platensis*. *The image is a close up of Spirulina cyano bacterium cells under a microscope* * Many pilot plants exist (Japan, US, Europe). * Sosa Texcoco (Mexico) set up the first pilot plant in 1973, increasing yield to 1,000 tonnes in 1982, exporting and preparing lozenges/capsules with added vitamins A and C. * The company supplied *Spirulina* to improve nutritional situations, making biscuits and confectionery with high protein content (Sasson, 1984). **(a) Benefits from *Spirulina* SCP:** * *Spirulina* can be harvested by simple methods such as nylon or cloth filters. * Filaments float due to gas vacuoles, so there is no problem of harvesting like *Chlorella*. **(Page 419)** * Minimum contamination in growth tanks (pH 8-11). * Heat drying is sufficient (thin cell wall), whereas spray drying for *Chlorella* and *Scenedesmus* is expensive. * UNIDO programme in Mexico (1980), Hyderabad (1988, 1990), and Indian Council of Medical Research found no adverse effects in multigeneration feeding tests. * *Spirulina* is highly digestible (85-95%) due to thin wall and low nucleic acid (4%). It contains high percentage of digestible proteins (62-72%), vitamins, amino acids. *The following text refers to table 18.2* **Table 18.2. Composition of multin (i.e. dried powder of *Spirulina fusiformis*) (constituents are in per 100 of powder)*** | A. Major constituents (%) (mg) | | | C. Minerals | | | ------------------------------- | ----- | ----- | --------------- | -------- | | Total protein | - | 64.6 | Calcium | - | 6.58 | | Fat | - | 6.7 | Phosphorus | - | 977 | | Crude fibre | - | 9.3 | Iron | - | 44.7 | | Carbohydrates | - | 16.1 | Sodium | - | 796 | | Calories | - | 346 | Potassium | - | 1.28 | | B. Vitamins | | | **D. Essential amino acids (%)** | | | Beta-carotene | - | 320,000IU | Lysin | - | 2.99 | | Biotin | - | 0.22 mg | Cystine | - | 0.474 | | Cyanocobalamin (B12) | - | 65.7 mg | Methionine | - | 1.38 | | Folic acid | - | 17.6 mg | Phenylalanine | - | 2.87 | | Riboflavin | - | 1.78 mg | Threonine | - | 3.04 | | Thiamin | | 0.118 mg | | | | | Tocopherol | | 0.773 IU | | | | * Analysed by Michelson Laboratories Inc., California, U.S.A. (1988) **(b) Mass Cultivation of *Spirulina* SCP:** * Two farm types: natural systems and constructed systems. * A third design exists (i.e. enclosed system using transparent tube) and is under development (Henrikson, 1990). * Semi-natural lake system: Sosa Texcoco Lake (Mexico) and Lake Chad (Africa) offer ideal environments. *The image shows a large outdoor pond cultivation the Spirulina species, and the following caption: Production of spirulina in pond.* **(Page 420)** * Semi-natural lakes product is often expensive and is is of low quality due to possible contamination by uncontrolled natural environmental factors. SCP of those lakes are good for use in animal feed and to feed fish Researches are in effort to refine powder and make product high product quality. *(ii) Artificially built cultivation system.* * Favourable climate exist in growing countries that helps benefit outdoor Spirulina production. Based on nutrient and water this helps group system into two * Clean water system. This system is more expensive because of construction of artificial cultivation farms * Shallow raceway ponds circulated with paddle wheels and high quality of nutrients. For fast growth of spirulina in water add NaNO3 and NaHCO3 is necessary * Initially pH of the water should be maintained to 8.5 this helps self adjust and elevate levels between 10 -10.5. At this levels contamination is very less * The Earthrise Spirulina Farm of California is the world's largest food-grade Spirulina farm this farm contains the area about 10 heactares produces with the capacity of and produces 120 tonnes annually. This Farm operates Japan, Thailand, Mexico, Taiwan, Israel, Vietnam, China and India. * Two cultivation centres exist in India. One Shri A.M.M. Murugappa Chettiar Research Central (MCRC), Madras, and the other at Central Food Technology and Research Institute (CFTRI), Mysore. Madras centre operates the biggest Spirulina farm in India and yields annual tone of 75. * Products marketed in multivitamin tablets, baby food and health food. * Waste water system - This system is used in India because high populated countries and its used to solve environment issue * human and animal wastes and sewage are used for growth in Spirulina wastes are added to digester to help solid particles settle Liquid effluent is a help to add Nutrients in the artificially constructed ponds * NaNO3 and NaHCO3 are mixed S. platensis is found to grow better in sewage amended with NaCO3 and nutrients in different proportion and also in diluted sewage *(Vijayan, 1988)* * Where the pond is over flowing, its screened from the pond is dried in a solar for food * Most suitable system used in third world countries where major source of pollution * R.D. Fox of France has developed the 'Integrated Health and Energy System Project' for poor countries to stop food malnutrition * Operated today in developing countries, India, West Africa and South America the system was established by Indo- France Govt. at Centre of Science for villages (CVS), Wardha (Maharastra) * The CVS distributes Spirulina cookies and nodules to malnourished children of local villages, has shown ver encouraging results **(Page 421)** *c) Requirements for Growth of Spirulina: Following are the requirements for growth of spirulina:* * Algal tanks. circular tanks are mostly perferred over the rectangular ones because of ease in handling. depth should be about 25cm. Open tanks are suitable for tropical and sub-tropical regions. * Light. Low light intensity is required at the beginning to avoid photolysis * Temperature: The temperature growth for optimum should be between 35-40 * pH: initially , culture should be maintained at 8.5 which increases automatically to 10.5 * Agitation: Agitation of culture is necessary to for good quality and better yield. *Harvesting : used by mesh steel screens * Drying: it has a thin wall. sun drying is the most suitable and economical. * Yield: An average yield of 8-12 g Spirulina powder has been obtained in india and other countries * Warmer climate produces 20 g/m * Avoiding contamination: * to about 5x105 propagules per gram (Venkataraman and Becker, 1985). powder is packed and sealed in bottles *Single Cell Protein: Single cell protein of Spirulina is used as below:* * protein rich source for diet(60-72%), vitamins, fibres etc. * food for children growing countries * the Village Health and product is being disturbed to to under-nourished children contains as much nutrition as one kg assorted vegetable. * As health food: Sosa texaco is very popular and exported to europe * essential and taken those who control obesity. The MCRC has project to help balance health * theapeutic and natural medicine. spirulina possess medicinal properties,social weight, **(Page 422)** * level in blood,good source B-careton * UN to increased lactation * In cosmetics , herbal face * PRODUCTION OF BACTERIAL & BIOMASS * source minutes source source *Shell Research limited to from or *Several ATCC butane *Taiwan cellulose wastes. Procedure for Production *medium to biomass: Imperial the contain