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The product (S)-p-chlorodiphenylmethanol is obtained through stereoselective reduction of p-chlorobenzophenone using Debaryomyces marama cells, immobilized on Raschig rings. This process involved continuous fermentations in bioreactors for a period of 10 days. The conversion was 86% with a volumetric productivity of 0.248 litre−1 d−1. Comparative experiments with D. marama cells, incorporated in alginate, k-carrageenan or agar–agar gels were also performed. These results demonstrated superiority of the immobilization on ceramic carriers compared to other methods. Passive immobilization of D. marama cells on ceramic carriers has many advantages in comparison with gel-incorporation of the cells. For example, during a long bioreactor run, only a limited amount of cells could remain incorporated within the gel. Therefore immobilized cell preparations will be a convenient methodology in the production of optically active compounds such as pharmaceutical drugs.

The keratinase production by the thermophilic actinomycete strain Thermoactinomyces candidus was induced by sheep wool as the sole source of carbon and nitrogen in the cultivation medium. For complete digestion of wool by the above strain, both keratinolytic serine proteinase and cellular reduction of disulfide bonds were involved. Evidence was presented that substrate induction was a major regulatory mechanism and the keratinase biosynthesis was not completely repressed by addition of other carbon (glucose) and nitrogen (NH4Cl) sources. The enzyme was purified 62-fold by diethylaminoethyl - anion exchange and Sephadex G-75 gel permeation chromatographies. Sodium dodecyl sulfate - polyacrylamide gel electrophoresis indicated that the purified keratinase is a monomeric enzyme with a molecular mass of 30 kDa. The pH and temperature optima were determined to be 8.6 and 70°C, respectively. The purified thermophilic keratinase catalyses the hydrolysis of a broad range of substrates and displays higher proteolytic activity against native keratins than other proteinases. Ca2+was found to have a stabilizing effect on the enzyme activity at elevated temperatures.Key words: wool degradation, keratinolyic actinomycetes, keratinase, Thermoactinomyces candidus.

Different possibilities for converting pregnenolone triacetate to prednisolone using immobilized preparations of Flavobacterium dehydrogenans, Curvularia lunata and Arthrobacter simpelex in a fixed-bed loop reactor were investigated. The effects of the carrier, substrate concentration, pH and temperature on the rate of the substrate conversion were studied also. The biotransformations were performed with a continuous or semicontinuous substrate supply. A convenient pathway for the formation of prednisolone is proposed on the basis of the results obtained.

The production process for Arthrobacter simplex with high specific hydrocortisone Δ 1 -dehydrogenase activity was improved by medium optimization in parallel shake flask experiments. Using a genetic algorithm, the concentrations of 12 medium components (mineral salts and amino acid) were optimized within 144 experiments to give maximum specific hydrocortisone Δ 1 -dehydrogenase activity and biomass yield (full experimental plan : 1.5 x10 14 experiments). The specific hydrocortisone Δ 1 -dehydrogenase activity was improved by a factor of 4.5 to 1800 U g -1 . With the optimized medium composition in a stirred tank reactor for batch production of A. simplex, a specific hydrocortisone Δ 1 -dehydrogenase activity of 2000-3000 U g -1 dry biomass was achieved depending on harvest time (previously reported data : 18-37 U g -1 ).

Diamond possesses a number of outstanding properties which make it a perspective material as platform for preparation of biosensors. The diamond surface needs to be activated before the chemical attachment of crosslinkers with which biomolecules can interact. In the current work we have investigated the modification of ultrananocrystalline diamond/amorphous carbon (UNCD/a-C) films by oxygen and ammonia plasmas. Afterwards the layers were functionalized in a further step to obtain thiol-active maleimide groups on the surface. We studied the possibility for direct binding of maleimide to terminal OH-groups on the UNCD surface and for silanization with 3-aminopropyltriethoxysilane (APTES) to obtain NH2-groups for the following attachment of sulfosuccinimidyl 4-(N-maleimidomethyl)-cyclohexane-1-carboxylate (SSMCC). The thiol-bearing fluorescein-related dye 5-((2-(and-3)-S-(acetylmercapto) succinoyl) amino) fluorescein (SAMSA) was immobilized as an model biomolecule to evaluate the achieved thiol-activity by fluorescence microscopy. The results of the above mentioned surface modification and functionalization steps were investigated by Auger electron spectroscopy (AES) and contact angle measurements.

Fermentation of a mixture of 3,17α,21-triacetoxy-3,5-pregna-diene-20-one and 17α ,21- diacetoxy-4-pregnene-3,20-dione with Flavobacterium dehydrogenans ATCC 13930 led to 17α-acetoxy-21-hydroxy-4-pregnene-3,20-dione as the main product and the novel 17 aacetoxy- 6β,21-dihydroxy-4-pregnene-3,20-dione and 17α-acetoxy- 6α ,21-dihydroxy-4-pregnene- 3,20-dione as the minor ones. 6 -Hydroxylation was not found so far with this strain. The finding is in good accordance with the model of 6 -hydroxylation of steroids proposed for fungi by Holland et al

The biotransformation of various alkaloids is reviewed. Special attention is paid to problems in microbial transformations and the different solutions offered by different authors. The biosynthetic potential of the strains selected for biotransformations is compared to the reaction observed in microbal oxidation. An outlook to future developments in other areas, especially from active site modelling, genomics and microbial ecology, are discussed which may contribute to problems in biotransformations.

Isosorbide-5-mononitrate and isosorbide-2-mononitrate, the metabolites of isosorbide dinitrate, were studied for their effects on the contractile and electrical activity and on the content of cyclic nucleotides in isolated heart muscles of guinea-pig and dog. Isosorbide-5-mononitrate at all concentrations tested and isosorbide-2-mononitrate at low concentrations did not produce significant changes in the mechanical activity of guinea-pig heart preparations. Isosorbide-2-mononitrate in concentrations above 10−4 m inhibited the contractility and shortened the action potential of guinea-pig and dog heart muscle. Neither mononitrate had an effect on cAMP concentration but both induced a significant elevation of cGMP content in guinea-pig heart tissue, the effect of isosorbide-2-mononitrate being greater.

A simple method for immobilizing cells of Acetobacter suboxydans by adsorption on inorganic sintered glass carriers is described. The immobilized cell preparations exhibited 100% of the initial activity when converting d-sorbit to l-sorbose. This sintered glass was used in a fixed-bed loop reactor with a working volume of 0.2 l for semicontinuous and continuous experiments. A prolonged working life span was achieved, which could possibly satisfy requirements for scaled-up operations.

The nano-scale holographic gratings ware recorded in 29 nm and 56 nm thick As2S3 films. The chalcogenide layers were deposited on a transparent chromium electrode with thickness 10 nm, produced on a glass substrate. Both chromium and chalcogenide films were deposited in one vacuum cycle by e-beam and thermal evaporation, respectively. The diode 532 nm diode laser was used as a light source in the present holographic experiments. The total internal reflection arrangement (Stetson-Nassenstein) was used in holographic recordings. The reference beam was totally reflected from the air-As2S3 boundary surface by an input glass prism. The object beam was normally incident on the recording medium. The corona charging was performed by a needle fixed at the distance of 1 cm from the holographic recording medium by applying a – 5 kV voltage. The diffraction efficiency increased from 9 to 30 times when the corona discharge was applied during the holographic recording, in comparison to the uncharged recording. The possible reason of the observed effect is discussed on the basis of the Franz-Keldysh effect and Moss rule.

The biotransformation of various alkaloids is reviewed. Special attention is paid to problems in microbial transformations and the different solutions offered by different authors. The biosynthetic potential of the strains selected for biotransformations is compared to the reaction observed in microbal oxidation. An outlook to future developments in other areas, especially from active site modelling, genomics and microbial ecology, are discussed which may contribute to problems in biotransformations.

Debaryomyces marama enantioselectively reduces p-Cl-benzophenone to the S-alcohol with high enantiomeric excess.

4-Hydroxymethylquinoline was isolated from Polyporus versicolor and P. sanguineus .

The biosynthesis of radicinin, which is a mycotoxin excreted from Curvularia lunata cultures, was activated by a system that maintains a constant level of acetate in the medium. The system consists of tertiary alkylacetates sparingly soluble in water, and esterases secreted into the medium by the fungus.

Product crystal formation has been observed for the transformation of pregnenolone triacetate to Reichstein-S-17α-acetate with Flavobacterium dehydrogenans ATCC 13930 at a concentration of 20 g/l, and for the conversion of hydrocortisone-17α-acetate to prednisolone-17α-acetate with Arthrobacter simplex ATCC 6946 (2 g/l). Hydrocortisone-17α-acetate was obtained from pregnenolone triacetate by a two-stage fermentation with F. dehydrogenans and Curvularia lunata NRRL 2380. At the concentration used (1 g/l) for the second stage, crystal formation of hydrocortisone-17α-acetate could not be observed. It was demonstrated that the progress of the first stage of the transformation may be studied by the powder diffraction technique. Crystal data and structures have been determined for five of the steroids involved in the above conversions.

Modifications of protecting groups and of the oxidative coupling conditions lead to pure crystalline intermediates in the synthesis of galanthamine derivatives and gave dienone A in better yields than reported before. The E -configuration of amide 3′ in crystalline state has been determined by X-ray diffraction. Streptomyces affinis 6737 reduces A to the optically active (−)-epigalanthamine derivative C, whose absolute configuration was determined by Bijvoet's method. Nematospora corylii CBS 2608 reduces to racemic B. With Ashbya gossypii IFO 1355 a mixture of racemic B and optically active C is obtained. some other microbial transformations are described.

Galanthamin is a medical important alkaloid. Its chemical synthesis gives a racemic product in low yields. Starting with a belladinderivative an enzymatic ring closure should lead exclusively to a chiral product possibly with the native structure. Although this reactions type is unknown in preparative biotransformations a large number of microorganisms were tested, unfortunately without success. On the other hand in the screen transformation products were found resulting from specific dealkylations of the subtrate. The type of metabolite formed was dependent on the fungi utilized for the transformation. Additionally two N-oxides were formed by Septomyxa affinis, one in good yield. It is possible that the chirality of this compound can direct the ring closure preferentially or exclusively to the desired stereoisomer of narwedine.

3-Desoxymorphinanes should be transformed by microbial hydroxylation of the aromatic ring to morphinanes. Instead of this reaction the investigated N-derivatives (H, CH3, COCH2OH and COCH2OCH2CH3) are reduced by several fungi to the 6-(R)-hydroxy structures. Rhizopus achlamydosporus cleaved additionally the ethoxy-acetyl-group to a hydroxy-acetate.