[Steroid transformation with immobilized microorganisms].

The application of immobilized microbial cells has been receiving increasing interest, in particular because of their potential for use in industrial fermentation processes and in analytical procedures. Since the first application of an immobilized microbial biocatalyst for steroid transformation in 1970 by MOSBACH and LARSSON many results have been published concerning the use of such type of biocatalyst in steroid biochemistry and steroid microbiology, respectively. The review deals with the present scientific state of the steroid transformations performed with immobilized biocatalysts, their applications and development trends. In particular the following aspects are discussed: 1(2)-dehydrogenation or hydrogenation, hydroxylation reactions, redox processes in 3,17- and 20-oxogroups, side chain splitting of sterols, 5 alpha-reduction, modification of cholic acid derivatives and the use of immobilized plant cells. The possibility for application of microbial membrane electrodes in steroid analysis has been shown. Up to now, many results of fundamental research are known. There are possibilities for producing expensive steroid derivatives in laboratory apparatus using immobilized biocatalysts. Some of the processes, described here, are of practical interest, and some of them are said to be used industrially, respectively.