Abstract: A process for the production of ergosterol and its intermediate products using recombinant yeasts and plasmids for transformation of yeasts is described.

Abstract: A process for the production of dulcitol by fermentative reaction of lactose by galactokinase-negative mutants of genus Kluyveromyces is described, which is characterized in that5 g to 25 g of glucose is added to the fermentation culture after substantial hydrolysis of the lactose per liter orthe fermentation is performed under the conditions of the resting-cell process.

Abstract: A process for the production of 17-oxosteroids by fermentative oxidation of 17.beta.-hydroxy steroids is described, which is characterized in that for the fermentation, a bacterial culture of the species Mycobacterium spec. NRRL B-3805, Mycobacterium spec. NRRL B-3683, Mycobacterium phlei NRRL B-8154 or Mycobacterium fortuitum NRRL B-8153 is used.

Abstract: The disclosure relates to a process for the preparation of L-amino acids of general Formula I ##STR1## wherein A means the residue of an amino acid molecule, from D,L-aminonitriles of general Formula II ##STR2## wherein A has the meaning given above, characterized by fermenting the .alpha.-aminonitriles with a culture of Actinetobacter calcoaceticus DSM 3875 and reacting the thus-obtained D,L-amino acid amides of general Formula III ##STR3## wherein A has the meaning given above, with a culture of a microorganism containing amino acid amide racemases and L-amino acid amide amidases.

Abstract: Process is described for the production of L-amino acids of general formula I ##STR1## in which R.sub.1 means an alkyl radical with at most 12 carbon atoms optionally substituted by hydroxy groups, mercapto groups, halogen atoms, amino groups, carbonyl groups or guanidino groups and/or interrupted by oxygen atoms, nitrogen atoms or sulfur atoms, and in the case of mercapto compounds of formula I also their dithio compounds, characterized in that the microorganism Nocardia spec. DSM 3306 or its enzymes are allowed to act on a D,L-imidazolidinedione derivative of general formula II ##STR2## in which R.sub.1 has the above-named meaning or, in the case of mercapto compounds of formula II, also in their dithio compounds.

Abstract: A process is disclosed for the purification of wastewaters containing biodegradable aliphatic compounds which is characterized in that these compounds are brought into contact with microorganisms capable of biodegradation immobilized by embedment in a gel-type organic polymer that does not denature the microorganisms.