Abstract: The invention relates to a process for the production of compounds of general formula (I), wherein R1 is a —NH-tert-butyl group or a 4-methyl-piperidino group, by bioconversion of compounds of general formula (II), wherein R1 is as described above, using a biocatalyst having steroid-&Dgr;1-dehydrogenase enzyme activity, wherein the activity of the enzyme needed for the bioconversion is produced by induction.

Abstract: The invention relates to a process for the production of compounds of general formula (I), wherein R1 is a —NH-tert-butyl group or a 4-methyl-piperidino group, by bioconversion of compounds of general formula (II), wherein R1 is as described above, using a biocatalyst having steroid-&Dgr;1-dehydrogenase enzyme activity, wherein the activity of the enzyme needed for the bioconversion is produced by induction.

Abstract: A mixing device, especially for a fermenter, capable of dispersing gas in a broth therein, in which a number of propeller mixers are provided on a vertically extending shaft. The lower propeller mixer is a gas dispersing mixer having a hollow hub and open channels on the blades extending from this hub and tapering outwardly. At least one intermediate propeller mixer has some blades shorter than others and of reverse flow direction, some blades having baffle bars on trail edges thereof. The upper propeller mixer has the longer blades without channels and flow modifying elements.

Abstract: Complex mixing system with stages consisting of propeller mixers of high diameter ratio, where the blades are provided with flow modifying elements, whereby the energy proportions spent on dispersion of the amount of gas injected into the reactor, homogenization of the multi-phase mixtures, suspension of solid particles, etc. and the properties corresponding to the rheological properties of the gas-liquid mixtures and to the special requirements of the processes can be ensured even in extreme cases. Open channels (5) opposite to the direction of rotation are on the blades (4) of the dispersing stage (2a) of the propeller mixers (2) fixed to a common shaft, where the channels (5) are interconnected with gas inlet (7). The angle of incidence of a certain part of the blades (4) of mixing stages (2b, 2d) used for homogenization and suspension is of opposite direction and the length is shorter and/or the angle of incidence is smaller than those of the other blades.

Abstract: Microbiological conversions of cyclodextrins are intensified by adding to the reaction mixture 0.2 to 3 moles of .alpha.-, .beta.- or .gamma.-cyclodextrin or an optical mixture thereof pro mole of the steroid substrate, before, at the beginning or during the conversion. The cyclodextrin if desired, can be removed after the reaction. In this way the reaction velocity can be increased, the reaction time is reduced, the substrate concentration in the solution, i.e. its solubility is increased or the so called product inhibition may be avoided. In certain cases of more alternatives the desired reaction can be catalyzed and in this manner the selectivity is increased.