Microorganisms biotransformation

Saeki, M. and N. Hashimoto, 1971. Microorganism biotransformation of terpenoids. Part II. Production of cis-terpin hydrate and terpineol from [Pg.904]

Biotechnological processes may be divided into fermentation processes and biotransformations. In a fermentation process, products are formed from components in the fermentation broth, as primary or secondary metabolites, by microorganisms or higher cells. Product examples are amino acids, vitamins, or antibiotics such as penicillin or cephalosporin. In these cases, co-solvents are sometimes used for in situ product extraction. 

Present states and future directions of the use of photosynthetic microorganisms, especially microalgae, for biotransformation are discussed. 

Illustrative examples of biotransformation reactions include the following, although it should be emphasized that other microorganisms may be able to degrade the substrates ... 

Before discussing some of the larger groups of microorganisms that have been implicated in biodegradation and biotransformation, brief comments are made on other groups of organisms that have hitherto attracted somewhat limited attention ... 

These are major groups of microorganisms that have achieved restricted prominence in discussions on biodegradation and biotransformation, and include both photolithotrophs and chemolithotrophs. Some brief comments on both are therefore justihed. 

Errecalde O, M Astruc, G Maury, R Pinel (1995) Biotransformation of butyltin compounds using pure strains of microorganisms. Appl Organomet Chem 9 23-28. 

Hopkins GD, L Semprini, PL McCarty (1993b) Microcosm and in situ field studies of enhanced biotransformation of trichloroethylene by phenol-oxidizing microorganisms. Appl Environ Microbiol 59 2277-2285. 

Table 1 shows examples of some of the microorganisms involved in different biotransformation processes [11]. The following sections cite some more recent examples of microbial transformation of biologically important compounds, especially alkaloids and nitrogen-containing compounds. 

Table 1 Some examples of the microorganisms involved in different biotransformation processes (modified from [11])... 

Some of the industrial biocatalysts are nitrile hydralase (Nitto Chemicals), which has a productivity of 50 g acrylamide per litre per hour penicillin G amidase (Smith Kline Beechem and others), which has a productivity of 1 - 2 tonnes 6-APA per kg of the immobilized enzyme glucose isomerase (Novo Nordisk, etc.), which has a productivity of 20 tonnes of high fmctose syrup per kg of immobilized enzyme (Cheetham, 1998). Wandrey et al. (2000) have given an account of industrial biocatalysis past, present, and future. It appears that more than 100 different biotransformations are carried out in industry. In the case of isolated enzymes the cost of enzyme is expected to drop due to an efficient production with genetically engineered microorganisms or higher cells. Rozzell (1999) has discussed myths and realities... 

Ecologically, copper is a trace element essential to many plants and animals. However, high levels of copper in soil can be directly toxic to certain soil microorganisms and can disrupt important microbial processes in soil, such as nitrogen and phosphorus cycling. Copper is typically found in the environment as a solid metal in soils and soil sediment in surface water. There is no evidence that biotransformation processes have a significant bearing on the fate and transport of copper in water. 

In some cases, microorganisms can transform a contaminant, but they are not able to use this compound as a source of energy or carbon. This biotransformation is often called co-metabolism. In co-metabolism, the transformation of the compound is an incidental reaction catalyzed by enzymes, which are involved in the normal microbial metabolism.33 A well-known example of co-metabolism is the degradation of (TCE) by methanotrophic bacteria, a group of bacteria that use methane as their source of carbon and energy. When metabolizing methane, methanotrophs produce the enzyme methane monooxygenase, which catalyzes the oxidation of TCE and other chlorinated aliphatics under aerobic conditions.34 In addition to methane, toluene and phenol have been used as primary substrates to stimulate the aerobic co-metabolism of chlorinated solvents. 

Biotransformation Product Final product Indication Reaction type Microorganism Process Ref. 

In order to extend the biocatalytic activities of the biotransformation processes and reduce the frequency of producing cell mass and undesirable side products, immobilized-cell technology has been successfully applied to the whole-cell biotransformation processes. In addition to the three commercial immobilized whole-cell biotransformation processes shown in Table 10.1, examples of immobilization of three different microorganisms for whole-cell biotransformations are shown below to demonstrate the broad application of the immobilized whole-cell biotransformation processes. 

One of the main obstacles for whole-cell microbial transformation in an organic solvent is its biocompatibility, which has led to screening for organic-solvent-tolerant microorganisms. Numerous organic-solvent-tolerant microorganisms have been found and their tolerance mechanisms have been reviewed [14,33,34]. Two-phase biotransformation systems have been successfully implemented for the production of pharmaceutically relevant metabolites. 

The few reports on bioremediation of colored effluents by yeasts usually mention nonenzymatic processes as the major mechanism for azo dye decolorization [5-10]. In a first approximation based on the cellular viability status, these processes can be divided into two different types bioaccumulation and biosorption. Bioaccumulation usually refers to an active uptake mechanism carried out by living microorganisms (actively growing yeasts). The possibility of further dye biotransformation by redox reactions may also occur due to the involvement of... 

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