Synthesis Using Microorganisms

For therapeutic use, riboflavin is produced by chemical synthesis, whereas concentrates for poultry and Hvestock feeds are manufactured by fermentation using microorganisms such as Jishbyagossypii and remothecium ashbyii which have the capacity to synthesi2e large quantities of riboflavin. 

The antitumor alkaloid ellipticine (5,1 l-dimethyl-6//-pyrido[4,3-b]carbazole) has been isolated from many species of Ochrosia and Aspidosperma. Ellipticine and its derivatives are highly active versus several experimental neoplasms, and the compound has been widely subjected to studies devoted to its total synthesis, the preparation of derivatives, and metabolism. Metabolic transformation studies with ellipticines have been conducted, using microorganisms, in vivo and in vitro... 

Selective Production of Xylanases by Cellulolytic Microorganisms. Until recently there was little information on common or separate genetic control of cellulase and xylanase synthesis in microorganisms (60). Studies on this subject were complicated by the fact that numerous microbial ceUulases and xylanases are non-specific with respect to cellulose and xylan as substrates. As could be expected from a comparison of both polysaccharide structures, non-specificity is more frequently observed with cel-lulases, because their substrate binding sites can easily accommodate substrate using an unsubstituted p-(l 4)-linked chain of D-xylopyranosyl units. 

Kiener, A., Roduit, J.P., and Gloeckler, R. 1996. Microbiological method for the synthesis of heteroaromatic caboxylic acids using microorganisms of the genus Alcaligenes. EP-B 0747486. 

The use of microbial systems as in vitro models for drug metabolism in humans has been proposed, as there are many similarities between certain microbial enzyme systems and mammalian liver enzyme systems. The major advantages of using microorganisms are their ability to produce significant quantities of metabolites that would otherwise be difficult to obtain from animal systems or by chemical synthesis, and the considerable reduction in operating costs compared with animal studies. 

The two parameters in Eq. (7-92) are the maximum specific growth rate pmax (h-1) and the saturation constant K, (g substrate/L). The value of K. is obtained as the substrate concentration at which p = 1h pm (see Fig. 7-6). The form of Eq. (7-92) is entirely empirical, but it incorporates two important features (1) At high substrate concentration the whole cell machinery is involved in cell synthesis, and the specific growth rate reaches a maximum pmax (2) at low substrate concentration formation of biomass is a first-order rate process (as in any other chemical reaction) and p -> (pmax/Ks)Cs. Note that for many commonly used microorganisms Ks is much... 

Biological synthesis of metal nanoparticles is environmentally friendly processes that do not use toxic chemicals. Biological processes are classified into three methods using microorganism such as bacteria and fungi, using enzyme, and using plant or plant extracts. 

Mortierella alpina is one of the most valuable sources of REFA. Many firms use microorganisms to synthesize oil with over 40% arachidonic acid. Controlling the synthesis of certain REFA by Mortierella alpina became possible after the obtaining mutants with varied desaturase activity (Certik et al., 1998). By modifying the culture conditions for this fungus, the PEFA composition could be considerably altered. For example, a reduction in temperature and supplementing the culture liquid with GLA stimulated the synthesis of ERA. 

The 3,6-diposition-substituted pyridine compounds are important intermediates for industrial synthesis, especially for production of some agricultural chemicals. This compound can be obtained by chemically synthesized from pyridine, but the process is accompanied by some by-products. Microbial hydroxylation of aromatic compounds is a very efficient method of regioselective reaction. Several methods have been reported for the preparation of 3,6-disubstituted pyridine using microorganisms. In 1985, Lehky et al. reported the microbial production of 6-hydroxynicotinic acid (6-HNA) from nicotinic acid (NA) by Achromobacter xylosoxydans Nagasawa et al. also prepared 6-HNA from NA by using Pseudomonas fluorescens TN5. 

Sadowski, Z., Maliszewska, I.H., Grochowalska, B., Polowczyk, I., Kozlecki, T., 2008. Synthesis of silver nanoparticies using microorganisms. Mater. Sci. Poland 26, 419-424. 

---