An industrial perspective fermentative bioreduction of aromatic ketones by Penicillium rubens VIT SS1 and Penicillium citrinum VIT SS2
TL;DR: In this paper, the fungi mediated asymmetric reduction of the ketone is one of the most promising tools for the synthesis of chiral alcohols, and many fungal cultures were isolated from the USA.
Abstract: Microbial mediated, especially the fungi mediated asymmetric reduction of the ketone is one of the most promising tools for the synthesis of chiral alcohols. Many fungal cultures were isolated from...
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TL;DR: In this article , Fusarium equiseti was used as a whole-cell biocatalyst for the selective transformation of S-(+)-carvone in the dill oil to cis-(-)-dihydrocarvones [cis-()-DHC] in nearly quantitative conversion.
Abstract: Biotechnologically produced flavours and fragrances are labeled as ‘natural’ and in great demand. In the current study, Fusarium equiseti was utilized as the whole-cell biocatalyst for the selective transformation of S-(+)-carvone in the dill oil to cis-(-)-dihydrocarvone [cis-(-)-DHC]. In an optimized condition (pH 5–6, dill oil 1.0 g/L and incubation period 24 h) F. equiseti produced S-(+)-carvone metabolites, dominated by cis-(-)-DHC (92–96% through gas chromatography-mass spectrometry or GC-MS) in nearly quantitative conversion (~99%). In the next step, distillation of the whole culture isolated the product in the form of cis-(-)-DHC rich (0.33 g/L) hydrosol; thus eliminating the use of organic solvent for the extraction and reducing the solvent soluble off-odour in the product. Detailed sensory analysis demonstrated the uniqueness of hydrosol aroma in reference to the dill oil and characterized it as sweet, minty, fresh, spicy and herbal. Headspace-GC-MS analysis supported by the odour activity value and sensory profile showed cis-(-)-DHC as the key odorant in the produced hydrosol. The developed bioconversion technique was novel in terms of its high selectivity towards cis-(-)-DHC and organic solvent-free downstream processing, producing a unique aromatic hydrosol.
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TL;DR: The Molecular Evolutionary Genetics Analysis (Mega) software implements many analytical methods and tools for phylogenomics and phylomedicine and has additionally been upgraded to use multiple computing cores for many molecular evolutionary analyses.
Abstract: The Molecular Evolutionary Genetics Analysis (Mega) software implements many analytical methods and tools for phylogenomics and phylomedicine. Here, we report a transformation of Mega to enable cross-platform use on Microsoft Windows and Linux operating systems. Mega X does not require virtualization or emulation software and provides a uniform user experience across platforms. Mega X has additionally been upgraded to use multiple computing cores for many molecular evolutionary analyses. Mega X is available in two interfaces (graphical and command line) and can be downloaded from www.megasoftware.net free of charge.
21,952 citations
TL;DR: Fundamental aspects of the C-F bond are explored to rationalise the geometry, conformation and reactivity of individual organofluorine compounds.
Abstract: Fluorine is the most electronegative element in the periodic table. When bound to carbon it forms the strongest bonds in organic chemistry and this makes fluorine substitution attractive for the development of pharmaceuticals and a wide range of speciality materials. Although highly polarised, the C–F bond gains stability from the resultant electrostatic attraction between the polarised Cδ+ and Fδ– atoms. This polarity suppresses lone pair donation from fluorine and in general fluorine is a weak coordinator. However, the C–F bond has interesting properties which can be understood either in terms of electrostatic/dipole interactions or by considering stereoelectronic interactions with neighbouring bonds or lone pairs. In this tutorial review these fundamental aspects of the C–F bond are explored to rationalise the geometry, conformation and reactivity of individual organofluorine compounds.
2,689 citations
TL;DR: This work on the stereospecificity of microbiological reductions of alicyclic ketones led us to take an active interest in the enzymic reduction of carbonyl compounds and theenzymic oxidation of alcohols, thus distinguishing it from "substrate stereos pecificity", a term reserved for the selectivity of the enzyme for enantiomeric or diastereomeric substrates.
Abstract: Our work on the stereospecificity of microbiological reductions of alicyclic ketones led us to take an active interest in the stereospecificity ofthe enzymic reduction of carbonyl compounds and the enzymic oxidation of alcohols. Some micro-organisms, e.g. Curvularia falcata, reduce a great nurober of mono-, biand tri-cyclic ketones, of widely varying structures, to the corresponding alcoholsl. If such a microbiological reduction engenders a new asymmetric carbon atom, then often only one of the two possible epimeric products is formed. W e call this type of stereospecificity \"product stereospecificity\", thus distinguishing it from \"substrate stereospecificity\", a term reserved for the selectivity ofthe enzyme for enantiomeric or diastereomeric substrates. Such highly stereospecific microbiological reductions of racemic or meso carbonyl compounds Iead to mixtures of optically active diastereomeric alcohols which can be separated by chromatography. Figure 1 shows the
559 citations
TL;DR: In this article, a review of recent advances in the asymmetric reduction of ketones by biocatalysts is presented, with a discussion on recent developments in methodologies to control enantioselectivities of catalytic reactions.
Abstract: Herein we review recent advances in the asymmetric reduction of ketones by biocatalysts. Included are discussions on recent developments in methodologies to control enantioselectivities of catalytic reactions, and examples of practical applications that reduce various types of ketones are also shown.
458 citations
TL;DR: The present review highlights biotechnological processes for the production of chiral alcohols by reducing prochiral ketones with whole cells by focusing on conversion, yield, enantiomeric excess, and process strategies, e.g., the application of biphasic systems.
Abstract: Enzymes are able to perform reactions under mild conditions, e.g., pH and temperature, with remarkable chemo-, regio-, and stereoselectivity. Due to this feature the number of biocatalysts used in organic synthesis has rapidly increased during the last decades, especially for the production of chiral compounds. The present review highlights biotechnological processes for the production of chiral alcohols by reducing prochiral ketones with whole cells. Microbial transformations feature different characteristics in comparison to isolated enzymes. Enzymes that are used in whole-cell biotransformations are often more stable due to the presence of their natural environment inside the cell. Because reductase-catalyzed reactions are dependent on cofactors, one major task in process development is to provide an effective method for regeneration of the consumed cofactors. Many whole-cell biocatalysts offer their internal cofactor regeneration that can be used by adding cosubstrates, glucose or, in the case of cyanobacteria, simply light. In this paper, various processes carried out on laboratory and industrial scales are presented. Thereby, attention is turned to process parameters, e.g., conversion, yield, enantiomeric excess, and process strategies, e.g., the application of biphasic systems. The biocatalytic production of chiral alcohols utilizing isolated enzymes is presented in part I of this review.
216 citations