Single Cell Protein SCP

After the process of fermentation is over, the exhausted bacteria can be separated from the broth by filtration. This cell mass has a number of names, such as microbial biomass or single cell protein (SCP). Microbial biomass is a side product of all fermentation processes but in some cases it is actually the sole target product. Bacterial cells have a high content of protein, but are low in fat and cholesterol. This explains the names single cell protein (SCP) or microbial protein. SCP is mainly used as an additive in animal feed to enhance protein content. In principle, it is also safe for human food use, but the acceptance has been low until now. 

For SCP production it is desired to optimize the fermentation conditions for maximum cell growth. This means that sufficient carbon, nitrogen, water, and other nutrients must be supplied to keep the cells growing at the highest possible rate. An efficient addition of oxygen is 

This chapter concentrates on the possibility of producing SCP from petrochemical feed stocks, such as n-paraffin, methane, or methanol. Between 1960 and 1980, the idea to produce SCP from crude oil sources found a lot of attention and several large-scale plants with capacities of several 100,00 tons/year were built, for instance in southern Italy. Hopes were high at the time, but the development made only slow progress. One of the reasons could be the choice of the location, which is far away from both, the source of the feedstock and the consumers of the product. Another is that oil and natural gas are expensive feed stocks, because they also have other uses. Anyway, the technology for protein production from chemicals exists and may be applied with more success in other areas of the world, where more favorable starting conditions exist. 

The fermentation is usually continuous it proceeds under sterile conditions, at constant temperature, and is started with a defined starter culture to avoid side products as far as possible. Several processes were developed Shell had originally introduced a process that used methane (natural gas) as the feedstock for SCP production. The microorganisms are cultured in an aqueous medium at temperatures of 42 to 45°C and at a pH value of 6.8 under semisterile conditions. The final fermentation broth contains protein at a concentration of 25 g/L. The biomass is concentrated in large sedimentation tanks and then spray-dried. The mass balance equation (Eq. 9.3) shows that large volumes of oxygen are needed and that carbon dioxide and heat must be removed from the reactor. 

Several types of microorganisms are needed for an optimized continuous process. Methylococcus species metabohze the methane Pseudomonas, Nordica, and Moraxella species are present to convert other hydrocarbons and side-products. 

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Future Uses. The most recent uses for methanol can be found in the agricultural sector. Test studies are being carried out where methanol is sprayed directly onto crops to improve plant growth. Methanol can be used as a carbon source for the production of single-cell protein (SCP) for use as an animal feed supplement. The process has been commercially demonstrated by ICl at their BiUingham, U.K., faciUty. However, the production of SCP is not commercially practical at this time, in comparison to more conventional protein sources. 

Normal paraffins in this range are important intermediates for alkylating benzene for synthetic detergents production (Chapter 10). They are also good feedstocks for single-cell protein (SCP). 

FERMENTATION USING n-PARAEEINS (Single Cell Protein SCP)... 

The aim is to produce biomass or a mass of cells such as microbes, yeast and fungi. The commercial production of biomass has been seen in the production of baker s yeast, which is used in the baking industry. Production of single cell protein (SCP) is used as biomass enriched in protein.6 An algae called Spirulina has been used for animal food in some countries. SCP is used as a food source from renewable sources such as whey, cellulose, starch, molasses and a wide range of plant waste. 

Moebus, O., Teuber, M. and Reuter, H., Pneumatischer Wirbelschicht-Bioreaktor zur Herstellung von Einzellereiwei)3 (SCP) oder Ethanol [A gaseous fluidized bed for the production of single cell protein (SCP) or ethanol], Dechema-Monographien, 95 (1984) 181-194. 

A modification of the swelling apparatus was used to evaluate WPC, peanut protein, single cell protein (SCP), and chicken preen gland protein. Chicken protein exhibited the highest swelling values followed in decreasing order by peanut, SCP, and WPC products (15). 

The first persons to point out the possibility of computer monitoring of indirectly measured parameters were Yamashito, Hisashi, and Inagaki in 1969 (2). The method was described in a U.S. Patent in 1975 (3). Examples of the application of computer-aided indirectly measured parameters to the control and optimization of batch-fed Baker s Yeast fermentation were described by Jefferis and Humphrey in 1973 (4) and by Wang, Cooney, and Wang in 1977 (5). Background and detailed history of this application can be found in the review by Humphrey (1). The work to be discussed in this report is another example of computer-aided indirectly measured cell biomass and growth rate and the use of this information in the feed back control of the carbon substrate, ethanol, in a process for the production of a yeast single cell protein (SCP). 

Other New Markets. Moving away from the automobile fuel market, ICI and Phillips Petroleum have developed single cell protein (SCP) products made by the growth of a microorganism that uses methanol as the sole source of carbon nutrient. These SCP s aim at the animal feed market as high protein additives in competition with skimmed milk powder and fish meal. If this process proves successful it offers a potential future additional consumption of methanol, although not in the same league as the possible fuel market. 

Without knowing the detailed metabolic pathways, many fermentative products today are obtained via aerobic fermentation processes. Probably the largest scale, single product aerobic fermentations are those used to produce single cell protein (SCP), or yeast biomass from hydrocarbons [63]. Here, an aerated yeast suspension in water, which contains trace nutrients is used to generate yeast biomass from gas oil, a mixture of straight chain hydrocarbons in the Cn to C20 range (Eq. 16.23). 

FIGURE 16.9 Details of the ICI single cell protein (SCP) process based on methanol. Reprinted from Prave and Faust[67], courtesy of the Royal Society of Chemistry. 

Single cell protein (SCP) manufacture for use as an animal feed supplement... 

Very little attention has been given to the possibilities for anaerobic production of single-cell protein (SCP) from cheap carbohydrate residues (1,2). The reason for dismissing any anaerobic process is that cel yields, according to classical Embden-Meyerhof catabolism, are only 10 to 15% of the substrate fermented. In contrast, aerobic cell yields of 50 to 60% are easily obtainable. 

Determine how coproducts might affect the overall economics of biological hydrogen production, specifically on the co-production of single-cell protein (SCP). 

Yeast single-cell protein (SCP) and yeast extract (YE), in particular, are two products that have many food, feed, pharmaceutical, and biotechnological applications. However, many of these applications, e.g., yeast extract as nutrient source for industrial growth of... 

Pretreatment of llgnocelluloses Is the first requirement for the growth of the microorganisms which are unable to grow on the untreated substrate but which, otherwise, grow rapidly and make certain products l.e. Trlchoderma reesel for cellulases and Chaetomlum cellulolytlcum for single-cell protein (SCP) Pretreatments that Increase the digestibility of... 

Proteins can be commercially produced from different substrates by a series of microbiological syntheses. Yeasts can convert straight-chain paraffins, gas oils, ethanol, or cellulose to single cell proteins, SCP. SCP can also be obtained by converting paraffins, gas oils, methanol, ethanol, methane, or cellulose with bacteria sugar, starches, and other carbohydrates... 

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