Fermentation essential

The vitalists theory of fermentation (essentially dependent on living cells) by Pasteur... 

H2N-CH2 [CH2j3.CH(NH2) COOH. Colourless needles, m.p. 224 C (decomp.), very soluble in water, insoluble in alcohol. L-(-H)-Lysine is one of the basic amino-acids occurring in particularly large quantities in the protamine and histone classes of proteins. It is an essential amino-acid, which cannot be synthesized by the body and must be present in the food for proper growth. It can be manufactured by various fermentation processes or by synthesis. 

Because of the simplicity of swiae and poultry feeds, most feed manufacturers add vitamins (qv) and trace minerals to ensure an adequate supply of essential nutrients. Amino acids (qv) such as methionine [7005-18-7] lysiae [56-87-17, threonine [36676-50-3] and tryptophan [6912-86-3], produced by chemical synthesis or by fermentation (qv), are used to fortify swiae and poultry diets. The use of these supplements to provide the essential amino acids permits diets with lower total cmde proteia coateat. 

Lujuefaction. Eigure 21 outlines most of the biomass Hquefaction methods under development. There are essentially three basic types of biomass Hquefaction technologies, ie, fermentation, natural, and thermochemical processes. 

Alcohol dehydrogenase (5) and leucine a-ketoglutarate transaminase (33,34) contribute to the development of aroma during black tea manufacturing. Polyphenol oxidase and peroxidase are essential to the formation of polyphenols unique to fermented teas. 

Purification. The objective of crystallization also can be purification of a chemical species. For example, L-isoleucine (an essential amino acid) is separated by crystallization from a fermentation broth that has been filtered and subjected to ion exchange. The recovered crystals contain impurities deleterious to use of the product, and these crystals are, therefore, redissolved and recrystalHzed to enhance purity. 

Selenium is a vital microelement for people. It has dual properties. Selenium is an essential nutrient at low concentration levels and it becomes toxic at higher concentration levels. Deficiency of selenium results in weakness and hard diseases. Selenium is a building material of many hormones and ferments it neutralizes free radicals, radioactive radicals in organism. The range of selenium safety concentration in food and water is very narrow. The daily normal amount of human consumption of selenium is 10-20 p.g, maximum safe concentration of selenium in water is 5-10 p.g/1. It becomes toxic at 20-30 p.g and bigger content in different objects. 

During the stationary phase, the growth rate is zero as a result of the depletion of nutrients and essential metabolites. Several important fermentation produets (ineluding most antibioties) are produeed in the stationary phase. The stationary phase is followed by a phase where eells die or sporulate. During the death phase, there is a deerease in live eell eoneentration, whieh results from the toxie byproduets eoupled with the depletion of the nutrient. The number of viable eells usually follows an exponential deeay eurve during this period. 

The glucosides are compounds, which, under the influence of hydrolytic agents are decomposed into glucose or an allied aldose or ketose, and one or more other bodies, which, in the cases under consideration, form constituents of essential oils. The hydrolytic agents which bring about these changes are soluble ferments, such as diastases, enzymes and similar... 

A suitable fermentation medium contains water and a source of assimilable carbon and nitrogen and essential mineral salts. A typical medium suitable for production of chlorodemethyltetracycline is as follows ... 

Let us now consider the essentials of the fermentation process, largely as a revisionary exercise, before looking at the individual examples in detail. 

You should note that the figure in SAQ 5.1 is a simple outline as fermentations generally have more steps than indicated for example many have a multiple purification step. If the product were the whole cell (for example in single cell protein processes) then purification of the cell biomass would be necessary. If the required product were an intracellular compound then some stage of cell breakage would be essential. 

Bioprocess plants are an essential part of food, fine chemical and pharmaceutical industries. Use of microorganisms to transform biological materials for production of fermented foods, cheese and chemicals has its antiquity. Bioprocesses have been developed for an enoimous range of commercial products, as listed in Table 1.1. Most of the products originate from relatively cheap raw materials. Production of industrial alcohols and organic solvents is mostly originated from cheap feed stocks. The more expensive and special bioprocesses are in the production of antibiotics, monoclonal antibodies and vaccines. Industrial enzymes and living cells such as baker s yeast and brewer s yeast are also commercial products obtained from bioprocess plants. 

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