Biotechnology of forages: protein concentrates from bacteria.
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.
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Biotechnology of forages: proteins of microfungi
Proteins of microscopic fungi. Valuable source of well-balanced amino acid composition of proteins are the mycelium of many microscopic fungus. For its nutritional properties fungi proteins approaching soy protein and meat, so that can be used not only for the preparation of feed concentrates, but also as an additive in human food.
The raw material for commercial cultivation of microscopic fungi are usually the vegetable wastes containing cellulose, hemicellulose, lignin.
At the same time two critical issues are solving: getting protein mass and recyclingwastes of plant, woodworking and paper industry, which can be a source of environmental pollution. Particularly important to find active strains of microorganisms that can utilize carbon of lignin, which is highly resistant to degradation by microflora.
Currently in the process of studies, the fast-growing non-toxic strains of the meso-and thermophilic fungi from the genera Penicilium, Aspergillus, Fusarium, Trichoderma for industrial cultivation are selected. Mycelium cells of these fungi have a thin cell wall owing to what it is a very well-digested in the gastrointestinal tract of animals. They contain in their composition complex of aromatic substances rich in vitamins and easily digestible lipids.
As compared with yeast proteins microscopic fungi contain high amounts of sulfur amino acids and fungi proteins have the better digestibility. Concentration of nucleic acid in fungi mycelium (1-4% of dry weight) is almost the same as in the tissues of the plant. At the same time in the biomass of fungi protein is much less than in yeast (20-60% of dry weight) and fungi grow more slowly (doubling biomass in 4-16 hours, whereas in yeast 2-3 hours).
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