Aureobasidium subglaciale F134 is a bifunctional whole-cell biocatalyst for Baeyer-Villiger oxidation or selective carbonyl reduction controllable by temperature

The microbial production of either ester/lactones or enantio-enriched alcohols through Baeyer-Villiger oxidation or stereoselective reduction of ketones,respectively,is possible by using whole cells of A.subglaciale F134 as a bifunctional biocatalyst.The chemoselective pattern of acetophenone biotransformation catalyzed by these cells can be regulated through reaction temperature,directing the reaction either towards oxidation or reduction products.The Baeyer–Villiger oxidation activity of A.subglaciale F134 whole cells is particularly dependent on reaction temperature.Acetophenone was transformed efficiently to phenol via the primary Baeyer–Villiger product phenyl acetate at 20℃ after 48 h with 100% conversion.In contrast,at 35℃,enantio-enriched(S)-1-phenylethanol was obtained as the sole product with 64% conversion and 89% ee.In addition,A.subglaciale F134 cells also catalyze the selective reduction of various structurally different aldehydes and ketones to alcohols with 40% to 100% yield,indicating broad substrate spectrum and good enantioselectivity in relevant cases.Our study provides a bifunctional biocatalyst systemthat can be used in Baeyer–Villiger oxidation aswell as in asymmetric carbonyl reduction,setting the stage for future work concerning the identification and isolation of the respective enzymes.

Magic Mushrooms: Screening for Novel Biocatalysts in the Phylum Basidiomycota

The ascending application of enzymes in organic synthesis creates a growing demand for novel biocatalysts. The applied methods for their identification range from microbial enrichment cultures over metagenome screenings to solely computational methods. In this communication, we demonstrate a straightforward screening approach for the detection of novel biocatalysts in fungi belonging to the phylum Basidiomycota. It basically relies on mincing of the whole fruit bodies of freshly collected mushrooms with subsequent direct screening. Suitability was demonstrated with eight different mushrooms which were investigated for carbonyl reductase activity on sterically demanding carbonyl compounds. The results indicate the presence of potentially useful carbonyl reductases (KREDs) in all tested fungi. Closer characterization of the preparation from pigskin poison puffball (Scleroderma citrinum) showed the presence of KRED exhibiting a broad substrate range. Thus, applicability of this low-tech screening approach could be verified in this study.

Synthesis of Open-Cage Fullerene Derivatives Containing Multiple Hydroxyl and Amino Groups on the Rim of the Orifice

Most of the known open-cage fullerene derivatives contain carbonyl and other relatively inert groups on the rim of the orifice.It is difficult to rationally design further reactions and attach other functional groups on to these open-cage derivatives.In the present work,two molecules of difunctional 1,4-benzenediamine have been incorporated into the rim of an open-cage C60 derivative through one amino group leaving the other amino group free for further functionalization.The difunctional 4-aminophenol reacted analogously to form an open-cage derivative with a free OH group each on the two phenyl rings.The amino and hydroxyl groups on the phenyl ring above the rim of the orifice showed similar reactivity as aniline and phenol.One of the carbonyl groups on the rim of the orifice could be selectively reduced by NaBH4 and P(OEt)3.The reduction reactions were reversible and the reduced products could be readily converted back to the carbonyl precursor.Thus,this redox process acts as a tool to fine tune the size of the orifice for host-guest studies.