What are the sources of carbon and the types of bacteria used in the production of protein concentrates
Protein concentrates from bacteria. Along with obtaining fodder yeast, bacterial protein concentrates with a raw protein content of 60-80% of dry weight are also of great importance for feed production. There are more than 30 species of bacteria that can be used as sources of high-grade fodder protein. Bacteria can grow biomass several times faster than yeast cells and the bacterial protein contains significantly more sulfur-containing amino acids, as a result of which it has a higher biological value than the yeast protein. The source of carbon for bacteria can serve as a variety of gaseous products (natural and associated gases, gas condensate, etc.), lower alcohols (methanol and ethanol), hydrogen. Most often on gas nutrient media, bacteria of the genus Methylococcus are grown, capable of utilizing up to 85-90% of the methane fed to the fermenter under optimal conditions. Due to the fact that the gas medium from methane and air is explosive and for the better utilization of methane by bacteria requires constant recycling, the production of fodder protein from gaseous products is quite complex and expensive. More widely used is the technology of growing bacterial protein mass on methanol, which can be easily obtained by oxidation of methane. When cultured on a nutrient medium containing methanol, the bacteria of the genera Methylomonas, Pseudomonas, Methylophillus are most effective. These bacteria are grown in a conventional fermenter using a liquid nutrient medium.
A large-scale production of feed proteins based on the use of methanol was first organized in England. Concern "ICI" produces a fodder protein preparation with the commercial name "Prutin". In Russia, a technology has also been developed for obtaining bacterial protein mass from methanol, the commercial name of the drug is Meprin. It contains up to 70-74% of the dry weight of proteins, up to 5% of lipids, about 10% of minerals, and 10-13% of nucleic acids. Based on the cultivation of bacteria of the genus Acinetobacter, the technology of obtaining fodder protein from ethanol (the name of the drug "Eprin"), which can also have a nutritional purpose, is being developed.
The high intensity of protein synthesis is characterized by hydrogen-oxidizing bacteria, capable of accumulating up to 80% of crude protein in their cells on a dry matter basis. These bacteria use the energy of hydrogen oxidation for the utilization of carbon dioxide, and some strains also for the assimilation of atmospheric nitrogen. For the cultivation of hydrogen-oxidizing bacteria, 70-80% of hydrogen, 20-30% of oxygen, and 3-5% of carbon dioxide are usually contained in the gaseous medium. The bacteria of the genera Pseudomonas, Alcaligenes, Achromobacter, Corinebacterium, etc., are highly effective in growing on such a gas medium. Generally, hydrogen for the production of a protein mass is obtained from water by electrolytic (electrolysis) or photochemical decomposition. Carbon dioxide can be used from the gaseous waste of any industrial product, as well as flue gases, which simultaneously solves the problem of cleaning the gas environment. The production of fodder protein based on hydrogen-oxidizing bacteria can also be organized near chemical plants where hydrogen is produced as a by-product.
What is the technology for obtaining protein mass from algal cells?
Feed proteins from algae. In Russia and a number of other countries, single-cell alga Chlorella and Scenedesmus, as well as blue-green algae from the genus Spirulina, are used to produce fodder protein, which are capable of synthesizing proteins and other organic substances from carbon dioxide, water and minerals by absorbing the energy of sunlight. For their cultivation it is necessary to provide certain modes of lighting and temperature, and also large volumes of water are required. Most often in natural conditions, algae are grown in southern regions using open-type swimming pools, but technologies for their cultivation in a closed system are also being developed.
Algae chlorella and spedesdemus require a neutral environment for their cultivation, their cells have a fairly dense cellulose membrane, which makes them worse digested in the animals. For better digestion, cellulose shells are destroyed by special treatment.
Spirulina cells are 100 times larger than chlorella, but they do not have a strong cellulose membrane and therefore are better digested in the animals. Spirulina is grown in alkaline medium (pH 10-11), under natural conditions in alkaline lakes. By the intensity of accumulation of biomass, algae, although inferior to fodder yeast and bacteria, significantly exceed agricultural plants. When grown in cultivators of open type with 1 hectare of water surface, up to 70 tons of dry biomass can be produced per year, while for wheat growing 3-4 tons, rice 5 tons, soybean 6 tons, maize 7 tons.
The technology for obtaining protein mass from algal cells includes the cultivation of industrial crops in cultivators of open or closed type, the separation of algae from the mass of water, the preparation of a commercial product in the form of a suspension, dry powder or paste-like mass. The process of separating algal cells from the mass of water is energy intensive, since it is necessary to process large volumes of liquid.
In Russia, the most common cultivation of chlorella, which is used to feed farm animals in the form of a suspension (1.5 g / l dry matter) or dry powder. The daily norm of the chlorella suspension when feeding young cattle is 3-6 l, adult animals - 8-10 l. When ruminant animals are added to the feed of chlorella flour, 50% of the vegetable protein can be replaced with protein from the algae.
Of great importance is the growth of algae on the drainage of industrial enterprises, thermal power plants, livestock complexes, since in these cases, along with the production of fodder protein, the problems associated with environmental protection are simultaneously being addressed. So, for example, the cultivation of a scene of spesdemus or chlorella on the drainage of livestock complexes for 15 days makes it possible to almost completely clear them of organic substances, the smell and color disappear. When algae are cultivated, industrial waste water or effluent from thermal power plants uses excess heat from these facilities, and carbon dioxide is utilized, formed as a by-product of technological processes and as a result of incineration of various wastes.
Cultivators for growing open algae are available in many countries. The largest chlorella company, Chlorella San Company, is in Japan. In Bulgaria, the waters of the thermal springs are cultivated with chlorella algae and spetesdemus, with Bulgarian scientists able to produce chlorella strains without a cellulose shell, so that the biomass of such cells is well digested in the animals. A significant amount of protein concentrates from alga spirulina are produced in the countries of central Africa and Mexico, where there are alkaline lakes. The largest producer of various products from biomass and spirulina proteins is the firm Coca Texcoco (Mexico). In Italy, technology is developed for the cultivation of spirulina cells on sea water and in cultivators of closed type.
Due to the fact that the biomass of algae of the genus Spirulina is easily digested by gastric juice enzymes and is characterized by a high protein content (up to 70% of dry weight), well balanced in amino acid composition, it is used in several countries for cooking foods, mainly confectionery products enriched protein.
Taking into account the importance of introduced into the industrial culture of algae as an additional source of high-grade protein for feeding agricultural animals and human nutrition, scientists of different directions - breeders, geneticists, biochemists - are conducting research on improving existing industrial strains of unicellular algae and obtaining new genotypes that should combine high intensity of photosynthesis, cold resistance, good digestibility, ability to synthesize a large number of b LCA better quality (higher content of essential amino acids), and dispose of the substrate fully. An important role in the implementation of such studies is given to methods of genetic engineering.
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