Abstract: Microorganism which can utilize an N-protected proline derivative of general formula (I) in the form of the racemate or one of its optically active isomers, R1 meaning —(CH2)2—COOH or, optionally substituted in each case, C1-C4 alkoxy, aryl or aryloxy, and R2 meaning hydrogen or hydroxy, as the only nitrogen, only carbon or only carbon and nitrogen source. These microorganisms can be used in a process for producing N-protected cyclic or aliphatic D-amino acid derivatives of general formulae (II) and (V), A together with —N— and —CH— and R3, R4 and R5 having the given meanings.

Abstract: A process for the production of 6-hydroxynicotinic acid from nicotinic acid by means of enzymatic hydroxylation in the presence of microorganisms of the genera Pseudomonas, Bacillus or Achromobacter. By maintaining a specific concentration range during the addition of nicotinic acid, the biomass formation can take place in the same process step as the product formation, without product losses occurring by further decomposition.