Common degradative pathways of morpholine, thiomorpholine, and piperidine by Mycobacterium aurum MO1: Evidence from H-1-nuclear magnetic resonance and ionspray mass spectrometry performed directly on the incubation medium

In order to see if the biodegradative pathways for morpholine and thiomorph oline during degradation by Mycobacterium aurum MO1 could be generalized to other heterocyclic compounds, the degradation of piperidine by this strain was investigated by performing H-1-nuclear magnetic rc:resonance directly with the incubation medium. Ionspray mass spectrometry, performed without p urification of the samples, was also used to confirm the structure of some metabolites during morpholine and thiomorpholine degradation. The results o btained with these tyro techniques suggested a general pathway for degradat ion of nitrogen heterocyclic compounds by M. aurum MO1. The first step of t he degradative pathway is cleavage of the C-N bond; this leads formation of an intermediary amino acid, which is followed by deamination and oxidation of this amino acid into a diacid. Except in the case of thiodiglycolate ob tained from thiomorpholine degradation, the dicarboxylates are completely m ineralized by the bacterial cells. A comparison with previously published d ata showed that this pathway could be a general pathway for degradation by other strains of members of the genus Mycobacterium.