Glycerol microbial synthesis

The previous section demonstrated the microbial synthesis of BIAs from aromatic intermediate such as dopamine or simple BIA norlaudanosoline. The production cost of using an expensive material as a substrate is relatively high. Hence, developing a new process that can convert BIAs from less expensive material such as renewable sources (e.g., glucose, glycerol) is important. 

These techniques, in which mutant strains are selected for their ability to overproduce metabolites, represent an important advance in the industrial development of microbial synthesis. Their use to improve amino-acid manufacture was not new they had already been used to improve the titres of antibiotics but the nature of the changes introduced into the metabolism of the mutated organisms could not be interpreted in the way that was possible for amino-acid synthesis. What is, perhaps, also apparent is that the technique of interfering with the metabolic pathway between aspartate and lysine is, in principle, no different from the use of sulphite to inhibit the synthesis of ethanol (section 6.2.1.2). In one case C. glutamicum overproduces lysine, while in the other S. cerevisiae will produce glycerol. 

Hekmat D, Bauer R, Fricke J (2003) Optimization of the microbial synthesis of dihydroxyacetone from glycerol with Gluconobacter oxydans. Bioprocess Biosyst Eng 26 109-116 Huffer S, Clark ME, Ning JC, Blanch HW, Clark DS (2011) Role of alcohols in growth, lipid composition, and membrane fluidity of yeasts, bacteria, and archaetu Appl Environ Microbiol... 

Glycerol kinase (GK E.C. 2.7.1.30) catalyzes the enantiospecific phosphorylation of glycerol to form sn-glycerol-3-phosphate, an important intermediate for the synthesis of phospholipids. The enzyme is inexpensive and stable when immobilized. Studies with enzymes from a variety of microbial sources have shown... 

Ephedrine is an alkaloid, a sympathomimetic amine with molecular formula Cjo Hi5 NOi, a molecular mass of 165.2, and the stmctural name (IR, 25)-2-methylamino-l-phenylpropan-l-ol. This bitter colorless or white solid-crystal is completely soluble in water, alcohol, chloroform, ether, and glycerol. Ephedrine is also produced by chemical synthesis and there is significant documentation of commercial ephedrine production using microbial biotransformation techniques [42]. Ephedrine has a structure close to methamphetamines, and its stimulant actions are comparable to epinephrine (adrenaline), a hormone produces by the adrenal glands that enhances heart rate and constriction of blood vessels in high-stress situations. Medicinal use of ephedrine began around 3000 B.C with the Chinese from md hudng, but its isolation was first reported in 1855 and its pharmaceutical application started in 1930 [22]. Studies on ephedrine s molecular structure show that two asynunetric carbon atoms are involved in ephedrine s molecular skeleton therefore, four optically active stereoisomers forms naturally occur as follows (IR, 2S)-(—)-ephedrine, (IS, 2R)-(+)-ephedrine, (IR, 2R)-( )-pseudoephedrine, (IS, 2S)-(+)-pseudoephedrine (Fig. 27.2). 

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