Yeast biotransformation

Fungal and yeast biotransformations of PAHs production of phenols by NIH shift... 

Similar work was performed by Shaw et al.3 in 1999 when they used FT-Raman, equipped with a charge coupled device (CCD) detector (for rapid measurements) as an on-line monitor for the yeast biotransformation of glucose to ethanol. An ATR (attenuated total reflectance) cell was used to interface the instrument to the fermentation tank. An Nd YAG laser (1064 nm) was used to lower fluorescence interference and a holographic notch filter was employed to reduce Rayleigh scatter interference. Various chemometric approaches were explored and are explained in detail in their paper. The solution was pumped continuously through a bypass, used as a window in which measurements were taken. 

P. Nikolova and O. P. Ward, Whole cell yeast biotransformations in two-phase systems effect of solvent on produd formation and cell structure, J. Ind. Microbiol. 1992, 10, 169-177. 

D Arrigo, P Fuganti, C., Pedrocchi Fantoni, G., and Servi, S. (1998) Extractive biocatalysis a powerful tool in selectivity control in yeast biotransformations. Tetrahedron, 54,15017-15026. 

Nikolova and Ward [72,73] studied production of phenylacetyl carbinol from benz-aldehyde and pyruvate by whole-cell yeast biotransformation in two-phase systems. For the biocatalyst preparation fresh pressed commercial baker s yeast (50 g) was suspended in 50 ml 0.05 M sodium citrate buffer (pH 6.0) and lyophilized. Aliquots of 300 mg of lyophilized cells were mixed witii 1 g celite and the mixture was resuspended in 0.05 M sodium citrate buffer (pH 6.0). The suspension was lyophilized again and stored at 4°C. Scanning electron micrographs of the carrier celite and yeast cells lyophilized on celite are given in Fig. 1. Prior to use, organic solvents purchased in anhydrous form were saturated with 0,05 M sodium citrate buffer (pH 6.0). The same buffer was used as an aqueous component of the biphasic systems. 

In current industrial practice, benzaldehyde is added to fermenting baker s yeast Saccharomyces cerevisiae) with resultant PAC production occurring from the yeast-derived pyruvate. Typically PAC concentrations of 12-15 g F are produced at yields of 65-70% theoretical in a 10-12 h biotransformation process. [2], Appreciable concentrations of benzyl alcohol are produced as by-product due to oxidoreductase activity in the fermentative yeast. 

MacGillivray AR, MP Shiaris (1993) Biotransformation of polycyclic aromatic hydrocarbons by yeasts isolated from coastal sediments. Appl Environ Microbiol 59 1613-1618. 

Schauer E, K Henning, H Pscheidl, RM Wittich, P Fortnagel, H Wilkes, V Sinnwell, W Francke (1995) Biotransformation of diphenyl ether by the yeast Trichosporon beigelii SBUG 765 Biodegradation 6 173-180. 

A cytochrome P450 has been purified from Saccharomyces cerevisiae that has benzo[a]pyrene hydroxylase activity (King et al. 1984), and metabolizes benzo[fl]pyrene to 3- and 9-hydroxybenzo[fl]pyrene and benzo[fl]pyrene-7,8-dihydrodiol (Wiseman and Woods 1979). The transformation of PAHs by Candida Upolytica produced predominantly monohydroxyl-ated products naphth-l-ol from naphthalene, 4-hydroxybiphenyl from biphenyl and 3- and 9-hydroxybenzo[fl]pyrene from benzo[fl]pyrene (Cerniglia and Crow 1981). The transformation of phenanthrene was demonstrated in a number of yeasts isolated from littoral sediments and of these, Trichosporumpenicillatum was the most active. In contrast, biotransformation of benz[fl]anthracene by Candida krusei and Rhodotorula minuta was much slower (MacGillivray and Shiaris 1993). 

Whereas the metabolism of aromatic hydrocarbons takes place by dioxygenation, their biotransformation by yeasts and fungi is normally initiated by monooxygenation to the epoxide followed by hydrolysis to the trani-dihydrodiols. Phenols may subsequently be formed either by elimination or by nonenzymatic rearrangement of the epoxide ... 

Octonol is an intermediate for the production of several optically active pharmaceuticals, such as steroids and vitamins. The asymmetric reduction of 2-octanone to (5)-2-octonol by baker s yeast was inhibited severely by substrate and product concentration of 10 him and 6 mM respectively. Whole-cell biotransformation of 2-octanone in a water-ra-dodecane biphasic system yielded a high product concentration of 106him with 89% ee in 96h [37],... 

Jadhav JP, Govindwar SP (2006) Biotransformation of malachite green by Saccharomyces cerevisiae MTCC 463. Yeast 23 315-323... 

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... 

To circumvent the cofactor regeneration problem, redox biotransformations are also carried out in whole cells - for example, baker s yeast [28, 29] or engineered Escherichia coli cells [30] - using the intracellular cofactor pool and inherent or recombinant regeneration systems. 

Variations for 5-hydroxy fluvastatin. Medium for growth on agar plates Plate Count Agar (Fluka/ Sigma Aldrich, Buchs, Switzerland) medium for preculture and main culture glucose 20 g L , soytone (Becton Dickinson) 15 g L , yeast extract 10 g L , pH adjusted to 6.5 with NaOH. Incubation time of main culture before fluvastatin addition 3 days biotransformation period 24 h. 

Analogous to the KRED reductions they can be performed as whole-cell biotransformations [48, 49] (baker s yeast, for example, contains a number of EREDs) or with isolated enzymes [50-52]. In the latter case the nicotinamide cofactor can... 

Finally, the yeast Yarrowia lipolytica is able to transform ricinoleic acid (12-hydroxy oleic acid) into y-decalactone, a desirable fruity and creamy aroma compound however, the biotransformation pathway involves fi-oxidation and requires the lactonisation at the CIO level. The first step of fi-oxidation in Y. lipolytica is catalysed by five acyl-CoA oxidases (Aox), some of which are long-chain-specific, whereas the short-chain-specific enzymes are also involved in the degradation of the lactone. Genetic constructions have been made to remove these lactone-degrading activities from the yeast strain [49, 50]. A strain displaying only Aox2p activity produced 10 times more lactone than the wild type in 48 h but still showed the same growth behaviour as the wild type. 

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