Fermentative syntheses

Fermentation/synthesized organic chemicals plants (generally moderate to large plants) ... 

Some industrial products are listed in Table 19.14. Chemical and fermentation syntheses sometimes are competitive, for instance, of ethanol, acetone, and butanol. 

Isolation Chemical synthesis Fermentation Synthesis / fermentatio n... 

Corynebacter, in ascorbic acid fermentation synthesis, 25 754 Corynebacterium glutamicum, fermentation products from,... 

Due to their fermentative synthesis, natural PHAs are strictly isotactic, featuring exclusively (/ )-configuration at the chiral stereocenter in the main chain. However, PHAs vary in their mechanical properties and can be grouped into two subcategories ... 

The industrial scale fermentative synthesis of PHA uses these pathways to convert the typical nutrients sugar or starch to PHB, but glycerol or palm-oil can also be applied. In addition, copolymers can be produced in this way but special microorganisms, growing condition, and additives are needed. Thus a statistic comonomer distribution starting from 0% (pure PHB) up to 90% co-monomer content can be achieved [35-38]. 

Fig. 8 Technical polymer work-up after fermentative synthesis [39]...

Production this way is thus complex and time consuming, therefore generating an extremely expensive material. Even if new and low-cost feedstocks are applied successfully in future, fermentative synthesis will remain high priced due to this work-up process, which cannot compete with a simple poly(olefin) production (Fig. 9). 

The disadvantages of all biochemical routes is the lack of variable tacticity in the polymer and, even more important, the need for time-consuming purification. PHB materials of feasible properties are only achieved with high production costs. In the 1990s, ICl sold a copolymer of 3-HB and 3-HV (BIOPOL) for about 10-20 /kg whereas the price of PP was less than 2 /kg. Therefore, a fermentative synthesis is feasible for smaller applications but not cannot compete with packaging materials such as poly(olefin)s [43 5] (Fig. 10). 

Reichstein-Griissner Sorbitol Fermentation Glucose Fermentation synthesis... 

The classical methods of chemical and fermentative synthesis and purification are augmented by the powerful genetically modified cellular systems of production, by transgenic animals and plants, as well as by sophisticated techniques of syntliesis, analysis, purification, such as chual catalysts, micro-reactors, and process intensification. 

As the raw material for LA fermentative synthesis is almost 34% of the total manufacturing cost, the use of cheap alternative sources has been extensively studied [123, 297]. In this respect, employment of paper sludge, lignocellulose, and starch material from agricultural residues and forestry resources are used. 

The synthesis of PLA and its cost-driving bottlenecks are presented in Fig. 4. The first step is the fermentative synthesis of (usually L-) LA with bacteria or yeast. Elegant reviews on this anaerobic fermentation are available elsewhere [55-58]. LA is further converted to its cyclic dimeric ester lactide via a two-stage process consisting of a pre-polymerization and a backbiting reaction (second frame in Fig. 4). This L,L-lactide is the acmal mmiomer for high molecular weight PLA. 

Fig. 4 Current industrial synthesis of (l-)PLA from carbohydrate feedstock the fermentative synthesis of L-LA the chemical two-step synthesis of the cyclic intermediate lactide and the polymerization to PL A. A pie chart shows a rough estimate of each of the frames contribution to the total production cost of PLA, from sugar to pellet...

Fermentative Synthesis of Structurally Complex Molecules by Incorporation of Labeled Precursors... 

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. 

Since (A) does not contain any other functional group in addition to the formyl group, one may predict that suitable reaction conditions could be found for all conversions into (A). Many other alternative target molecules can, of course, be formulated. The reduction of (H), for example, may require introduction of a protecting group, e.g. acetal formation. The industrial synthesis of (A) is based upon the oxidation of (E) since 3-methylbutanol (isoamyl alcohol) is a cheap distillation product from alcoholic fermentation ( fusel oils ). The second step of our simple antithetic analysis — systematic disconnection — will now be exemplified with all target molecules of the scheme above. For the sake of brevity we shall omit the syn-thons and indicate only the reagents and reaction conditions. 

Tetracyclines are produced by various Streptomyces strains and are extensively applied in human and veterinary medicine. They display a broad spectrum of antimicrobial activity in combination with low toxicity and can be applied orally. The most commonly prescribed tetracycline drugs are tetracycline itself and oxytetracycline, an oxygenated derivative, which are directly isolated from fermentation liquors, and doxycycline whose partial synthesis from oxy-... 

The autotropic pathway for acetate synthesis among the acetogenic bacteria has been examined (67). Quantitative fermentation of one mole of glucose [50-99-7] yields three moles of acetic acid, while two moles of xylose [58-86-6] C H qO, yields five moles. The glucose reaction is... 

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. 

The modem fermentation industries developed from the early era of antibiotics. Over 4000 antibiotics have been discovered since the 1950s. However, only about 100 are produced on a commercial scale and over 40 of these are prepared by a combination of microbial synthesis and chemical modifications. Antibiotics produced by fermentation and used as starting materials in chemical syntheses are given in Table 2. 

The complexity of the biochemical pathways, certainly for antibiotic synthesis, means that the careful and rigorous selection of the microorganism is the key to obtaining higher titers. However, most microorganisms only show thek tme potential when cultured under optimal fermentation conditions. Of... 

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