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The production of natural flavors by means of microorganisms is of great interest for the food and flavor industry, and by-products of the agro-industry are particularly suitable as substrates. In the present study, Citrus side streams were fermented using monokaryotic strains of the fungus Pleurotus sapidus. Some of the cultures exhibited a pleasant smell, reminiscent of woodruff and anise, as well as herbaceous notes. To evaluate the composition of the overall aroma, liquid/liquid extracts of submerged cultures of a selected monokaryon were prepared, and the volatiles were isolated via solvent-assisted flavor evaporation. Aroma extract dilution analyses revealed p-anisaldehyde (sweetish, anisic-and woodruff-like) with a flavor dilution factor of 218 as a character impact compound. The coconut-like, herbaceous, and sweetish smelling acyloin identified as (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone also contributed to the overall aroma and was described as an aroma-active substance with an odor threshold in air of 0.2 ng L-1 to 2.4 ng L-1 for the first time. Supplementation of the culture medium with isotopically substituted L-tyrosine elucidated this phenolic amino acid as precursor of p-anisaldehyde as well as of (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone. Chiral analysis via HPLC revealed an enantiomeric excess of 97% for the isolated product produced by P. sapidus.

Caryophyllene and longifolene are sesquiterpenes with characteristic aroma properties, which are primary constituents of essential oils and important ingredients commonly used in food, perfumery, cosmetics, detergents and pharmaceuticals, which create a worldwide market. ?-Caryophyllene and longifolene were converted through microbial biotransformation by using Wolfiporia extensa to a mixture of products over seven days at 25o C to be evaluated as potential aroma and antimicrobial agents. The characterization of transformation products was carried out by comparison of their GC-MS spectra and retention indices with that of published data (Wiley, NIST and ADAMS databases). As a result, microbial transformation reactions produced various volatile compounds mainly consisting of ketones, aldehydes and alcohol-bearing derivatives of ?-caryophyllene and longifolene. © 2019, Badebio Biotechnololgy Ltd. All rights reserved.

Ziel der Arbeit war es Enzyme unter Erhalt der katalytischen Aktivität mittels Zerschäumungsanalyse anzureichern. Als Modellenzyme dienten das extrazelluläre Enzym Laccase von Trametes spec. und Meerrettich-Peroxidase aus Armoracia rusticana. Zunächst wurde Laccase aus SNL-Nährmedium unter Variation verschiedener Prozessparameter im Batch-, Kreislauf-, Kolonnen- und kontinuierlichen Verfahren zerschäumt. Um die Effizienz der Zerschäumung zu steigern wurde das sog. Pinzetten-Verfahren entwickelt. Dieses Verfahren basiert auf Enzym-Ligand-Wechselwirkungen, welche auf die Komplexierung von Metallkationen im aktiven Zentrum des Enzyms mittels chelatisierendem Tensid zurückgeführt wurden. Durch die Integration des Pinzettenverfahrens in die Zerschäumungsanalyse konnte sowohl die Anreicherung von Laccase als auch von Meerrettich-Peroxidase deutlich gegenüber der konventionellen Batch-Zerschäumung gesteigert werden. The aim of the current work was to enrich active enzymes by foam fractionation. As model enzymes served laccase from Trametes spec. and horseradish peroxidase from Armoracia rusticana. At first, laccase was enriched from culture broth via commonly applied foam fractionation in batch-, cycle- and continous mode, under different constantly optimized process parameters. In order to increase the efficiency of enrichment, the so-called “tweezing foam fractionation” was developed. The tweezing foam fractionation is based on enzyme-ligand –interaction, which was ascribed to the chelation of the metal cation in the active center of the enzyme through chelating surfactants. The method successively increased the enrichment of laccse, which in furtherance could be validated by application of this principle on horseradish peroxidase.