Biotransformation plants

Plants have been shown to biotransform xenobiotic organic compounds (Komossa and Sandermann, 1995 Pflugmacher and Sandermann, 1998). Historically, much of the information on plant biotransformation of organic compounds has been obtained from studies examining intentionally applied chemicals such as herbicides and pesticides. More recently, the biotransformation of nonherbicide organics has been investigated... 

Plant biotransformation parallels liver biotransformation and is conceptually divided into three phases. Phase I typically consist of oxidative transformations in which polar functional groups such as OH, NH2, or SH are introduced. However, reductive reactions have been observed for certain nitroaromatic compounds. Phase II involves conjugation reactions that result in the formation of water soluble compounds such as glucosides, glutathiones, amino acids, and malonyl conjugates or water-insoluble compounds that are later incorporated or bound into cell wall biopolymers. In animals, these water-soluble Phase H metabolites would typically be excreted. In Phase III, these substances are compartmentalized in the plant vacuoles or cell walls. For additional details, the reader is referred to reviews on the subject by Komossa and Sandermann (1995), Pflugmacher and Sandermann (1998), and Burken (2003). Enzymatic conversion rates typically follow Michaelis-Menten kinetics and are temperature-dependent (Larsen et al., 2005 Yu et al., 2004,2005, 2007). 

Biotransformations are carried out by either whole cells (microbial, plant, or animal) or by isolated enzymes. Both methods have advantages and disadvantages. In general, multistep transformations, such as hydroxylations of steroids, or the synthesis of amino acids, riboflavin, vitamins, and alkaloids that require the presence of several enzymes and cofactors are carried out by whole cells. Simple one- or two-step transformations, on the other hand, are usually carried out by isolated enzymes. Compared to fermentations, enzymatic reactions have a number of advantages including simple instmmentation reduced side reactions, easy control, and product isolation. 

High cost of state-of-the-art fermentation/biotransformation plant. 

After uptake, lipophilic pollutants tend to move into hydrophobic domains within animals or plants (membranes, lipoproteins, depot fat, etc.), unless they are biotransformed into more polar and water soluble with compounds having low Metabolism of lipophilic compounds proceeds in two stages ... 

The reduction of ketones, aldehydes, and olefins has been extensively explored using chemical and biological methods. As the latter method, reduction by heterotrophic microbes has been widely used for the synthesis of chiral alcohols. On the contrary, the use of autotrophic photosynthetic organisms such as plant cell and algae is relatively rare and has not been explored because the method for cultivation is different from that of heterotrophic microbes. Therefore, the investigation using photosynthetic organisms may lead to novel biotransformations. 

The uptake and biotransformation of benzene from soil and the atmosphere has been studied in a nnmber of plants. It was shown that in leaves of spinach Spinacia oleraced) the label in -benzene was fonnd in mnconic, fnmaric, snccinic, malic, and oxalic acids, as well as in specific amino acids, and that an enzyme preparation in the presence of NADH or NADPH prodnced phenol (Ugrekhelidze et al. 1997). 

Occasionally, biotransformation in the absence of substantial biodegradation may be acceptable. Dicyclopentadiene is produced pyrolytically in petrochemical plants and has a nauseating and penetrating odor. Although it could be degraded by a mixed bacterial culture, the major part was transformed into a series of oxygenated compounds that were presumed to be less malodorous (Stehmeier et al. 1996 Shen et al. 1998). 

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. 

PEST. This code ( 3) was developed within the framework of Rensselaer Polytechnic Institute s CLEAN (Comprehensive Lake Ecosystem Analyzer) model. It includes highly elaborated algorithms for biological phenomena, as described in this volume (44). For example, biotransformation is represented via second-order equations in bacterial population density (Equation 5) in the other codes described in this section PEST adds to this effects of pH and dissolved oxygen on bacterial activity, plus equations for metabolism in higher organisms. PEST allows for up to 16 compartments (plants, animals, etc.), but does not include any spatially resolved computations or transport processes other than volatilization. 

Vanillin (4-hydroxy-3-methoxybenzaldehyde) is widely used in foods, beverages, perfumes and the pharmaceuticals industries. Biotransformation of isoeugenol from essential oil to vanillin represents an economic route for the supply of vanillin, which has a limited supply due to the availability of vanilli pod plants. The conversion yield of isoeugenol to vanillin by the whole-cell biotransformation process of Bacillus fusiformis was low due to the product inhibition effect. Adding resin HD-8 to the whole-cell biotransformation eliminated the product inhibition effect, yielding 8 gL 1 of vanillin in the final reaction mixture [27]. The resin HD-8 also facilitated the separation of vanillin from the used substrate. The recovered isoeugenol can be used for the subsequent biotransformation reaction. 

Giri A, Dhingra V, GiriCC, Singh A, Ward OP, Narasu ML (2001) Biotransformations using plant cells, organ cultures and enzyme systems current trends and future prospects. Biotechnol Adv 19 175-199... 

Extensive biotransformation studies have been conducted with the As-pidosperma alkaloid vindoline, but much less work has been done with monomeric Iboga and dimeric alkaloids from this plant. The long-standing interest in this group of compounds stems from the clinical importance of the dimeric alkaloids vincristine and vinblastine, both of which have been used for more than 2 decades in the treatment of cancer. Few mammalian metabolites of dimeric Catharanthus alkaloids have been characterized. Thus the potential role of alkaloid metabolism in mechanism of action or dose-limiting toxicities remains unknown. The fact that little information existed about the metabolic fate of representative Aspidosperma and Iboga alkaloids and Vinca dimers prompted detailed microbial, mammalian enzymatic, and chemical studies with such compounds as vindoline, cleavamine, catharanthine, and their derivatives. Patterns of metabolism observed with the monomeric alkaloids would be expected to occur with the dimeric compounds. 

Considerable success has been achieved in isolating plant tissue culture enzymes responsible for specific steps in the biosynthesis of a range of indole alkaloids (187-191). While the subject of biosynthesis is beyond the scope of this review, the value of such enzymes in catalyzing biotransformation reactions... 

Biotransformations of morphinan alkaloids have been reported for plant, fungal, and mammalian enzymatic systems with emphasis on rather specific reactions such as the reduction of ketones, N- and O-demethylation, and perox-idative transformations. Furuya et al. used immobilized tissue culture cells of Papaver somniferum to accomplish the selective reduction of codeinone (135) to codeine (136) (207) (Scheme 30). Suspension cultures of a well-established cell line of P. somniferum were grown for one week as a source of cell mass for immobilization in calcium alginate. The cells continued to live in the alginate matrix for 6 months maintaining their biological activity. The reduction of co-... 

The NM concentrations in U.S. and European influent are significantly less than the PCM concentrations and are in the range of 0.2-5 pg/L. MX and MK are the highest concentration NMs in influent [22]. In general, the amino metabolites of the nitromusks are not detected in influent because there is limited opportunity for biotransformation in transit to the wastewater treatment plants. 

Surfactants and their biotransformation products enter surface waters primarily through discharges from wastewater treatment plants (WWTPs). Depending on their physicochemical properties, surface-active substances may partition between the dissolved phase and the solid phase through adsorption onto suspended particles and sediments [1,2]. Several environmental studies have been dedicated to the assessment of the contribution of surfactant residues in effluents to the total load of surfactants in receiving waters. This contribution reviews the relevant literature describing the presence of linear alkylbenzene sulfonates (LASs) and in particular of their degradation products in surface waters and sediments (Table 6.3.1). 

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