Microbial biocatalysis

The perspectives for an increasing use of biotechnology processes (biocatalysis, microbial fermentation) for LMW fine chemicals are promising. Substitution of traditional chemicals by biotechnology processes constitutes the most important means for reduction of manufacturing cost for existing fine chemicals. By 2010,30-60% of fine-chemical production processes are expected to comprise a biotechnology step ... 

Biocatalysis Chemical reactions mediated by biological systems (microbial communities, whole organisms or cells, cell-free extracts, or purified enzymes aka catalytic proteins). 

Martinkova, L. and Kren, V. (2002) Nitrile- and amide-converting microbial enzymes stereo-, regio- and chemoselectivity. Biocatalysis and Biotransformation, 20,73-93. 

Vazquez-Duhalt, R. Fedorak, P. M., and Westlake, D. W. S., Role of Enzyme Hydrophobicity in Biocatalysis in Organic-Solvents. Enzyme and Microbial Technology, 1992. 14(10) pp. 837-841. 

Microbial reduction has been recognized for decades as a laboratory method of preparing alcohols from ketones with exquisite enantioselectivity. The baker s yeast system represents one of the better known examples of biocatalysis, taught on many undergraduate chemistry courses. Numerous other microorganisms also produce the ADH enzymes (KREDs) responsible for asymmetric ketone reduction, and so suitable biocatalysts have traditionally been identified by extensive microbial screening. Homann et have... 

As described in Section 4.2, traditional biotech processes—namely, biocatalysis and microbial fermentation—are used for the production of small molecules, whereas the modern cell culture methodology allows the production of HMW biopharmaceuticals. A growth rate of 10-15% per annum is expected for the biotechnological contribution, while the average increase of the pharmaceutical market remains below 10%. In terms of technologies, the demanding mammalian cell cultures are expected to grow fastest, followed by microbial fermentation. 

Draths, K.M. Knop, D.R. Frost, J.W. (1999) Shikimic acid and quinic acid replacing isolation from plant sources with recombinant microbial biocatalysis. J. Am. Chem. Soc., 121, 1603-4. 

Apphed biocatalysis has its roots in ancient China and Japan in the manufacture of food and alcohohc drinks. Without knowing, man utilized microbial amylases and proteases, in particrrlar for the production of soy-derived foods. In Etrrope too, applied biocatalysis has a long history. Cheese making has always involved the use of enzymes. As far back as about 400 BC, Homer s Iliad mentions the use of kid stomach for making cheese. It was discovered that milk, which was stored in a bag made of a stomach of a recently slaughtered calf, lamb or kid was converted into a semi-sohd substance. Upon pressing of this substance a drier material was obtained (namely cheese) which... 

Cephalosporins are -lactam antibiotics that block microbial cell wall synthesis. The original cephalosporin. Cephalosporin C, has only weak antibiotic activity. Therefore much more powerful second generation cephalosporins were developed by side-chain modification. Modifications at Cl are most effective but modifications at position 3 are also important so as to increase in vivo activity. Synthesis of the second generation cephalosporin cefuroxime requires the replacement of the C3 acetoxy side-chain of the precursor with a caibamate group. Chemical methods proceed via a hydroxylated intermediate which causes problems due to a tendency to lactonise at low pHs. Therefore development of a biocatalysis step was initiated in order to achieve selective reaction nnder mild conditions. 

Applied biocatalysis is older than written history. Ancient records, picturing the manufacture of foods and beverages, testily to the involvement of amylases and proteases from microbial, plant or animal origin, without the knowledge of those using them. These ancient applications can therefore be best described as an art and not as a technology or a scientifically defined method. 

Fig. 23.1 Microbial routes from natural raw materials to and between natural flavour compounds (solid arrows). Natural raw materials are depicted within the ellipse. Raw material fractions are derived from their natural sources by conventional means, such as extraction and hydrolysis (dotted arrows). De novo indicates flavour compounds which arise from microbial cultures by de novo biosynthesis (e.g. on glucose or other carbon sources) and not by biotransformation of an externally added precursor. It should be noted that there are many more flavour compounds accessible by biocatalysis using free enzymes which are not described in this chapter, especially flavour esters by esterification of natural alcohols (e.g. aliphatic or terpene alcohols) with natural acids by free lipases. For the sake of completeness, the C6 aldehydes are also shown although only the formation of the corresponding alcohols involves microbial cells as catalysts. The list of flavour compounds shown is not intended to be all-embracing but focuses on the examples discussed in this chapter... 

Lipases, which are noted for their tolerance of organic solvents, were obvious candidates for biocatalysis in ionic liquids. Indeed, stable microbial lipases, such as CaLB [8, 54, 55, 56] and Pseudomonas cepacia lipase (PcL) [28, 55, 57] were cat-alytically active in the ionic liquids of the l-alkyl-3-methylimidazolium and 1-alkylpyridinium families, in combination with anions such as [BF4], [PF6], [TfO] and [ Tf2N]. Early results were not always consistent, which may be caused by impurities that result from the preparation of the ionic liquid. Lipase-mediated transesterification reactions (Figure 10.3) in these ionic liquids proceeded with an efficiency comparable to that in tert-butyl alcohol [8], dioxane [57], or toluene... 

Biocatalysis/Biodegradation Database of the University of Minnesota Microbial metabolism of many chemicals http //www.labmed.umn.edu/umbbd/ index.html... 

Outline the pathway for microbial degradation of the detergent used in denaturing electrophoresis, sodium dodecyl sulfate (SDS). Hint See the Web site on Biocatalysis/Biodegradation. 

Wackett, L. P., and C. D. Hershberger. 2001. Biocatalysis and Biodegradation Microbial Transformation of Organic Compounds. ASM Press, Washington, DC. 

Draths, K.M. et al. Shikimic Acid and Quinic Acid Replacing Isolation from Plant Sources with Recombinant Microbial Biocatalysis. 3.3 1999 [116]... 

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