Common Degradative Pathways of Morpholine, Thiomorpholine, and Piperidine by Mycobacterium aurum MO1: Evidence from ¹ H-Nuclear Magnetic Resonance and Ionspray Mass Spectrometry Performed Directly on the Incubation Medium

Abstract

In order to see if the biodegradative pathways for morpholine and thiomorpholine during degradation by Mycobacterium aurum MO1 could be generalized to other heterocyclic compounds, the degradation of piperidine by this strain was investigated by performing 1 H-nuclear magnetic resonance directly with the incubation medium. Ionspray mass spectrometry, performed without purification of the samples, was also used to confirm the structure of some metabolites during morpholine and thiomorpholine degradation. The results obtained with these two techniques suggested a general pathway for degradation of nitrogen heterocyclic compounds by M. aurum MO1. The first step of the degradative pathway is cleavage of the CON 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 obtained from thiomorpholine degradation, the dicarboxylates are completely mineralized by the bacterial cells. A comparison with previously published data showed that this pathway could be a general pathway for degradation by other strains of members of the genus Mycobacterium.

Analysis of the nearly identical morpholine monooxygenase-encoding mor genes from different Mycobacterium strains and characterization of the specific NADH : ferredoxin oxidoreductase of this cytochrome P450 system

“…The detection of intermediates during morpholine degradation in Mycobacterium aurum MO1 and in an environmental Mycobacterium strain strongly indicates that the initial ring cleavage occurs at the C-N bond (Combourieu et al, 1998b(Combourieu et al, , 2000 , 1998). Studies have suggested that a cytochrome P450 catalyses the hydroxylation of the carbon atom of this bond (Combourieu et al, 1998a;Poupin et al, 1998Poupin et al, , 1999b).…”

Proteomics and metabolomics: The molecular make‐up of toxic aromatic pollutant bioremediation

“…The biodegradation pathways of morpholine, thiomorpholine, and piperidine by Mycobacterium aurum MO1 and Mycobacterium sp. RP1 have been elucidated by in situ 1 H 1D NMR [50,51,57]. A pathway for the degradation of benzo[a]anthracene by Mycobacterium vanbaalenii PYR-1 in liquid culture has been proposed using 1 H NMR and HPLC analysis [58].…”

A novel piperidine degradation mechanism in a newly isolated piperidine degrader <i>Pseudomonas</i> sp. strain KU43P

“…Microbial degradation by Gram-positive bacteria of heterocyclic secondary amines, including piperidine, has been reported mostly for members of the genus Mycobacterium, with very few reports for non-Mycobacterium species (Combourieu et al, 2000;Kim et al, 2006;Knapp et al, 1996;Poupin et al, 1999a, b;Trigui et al, 2003). The degradation pathways for compounds of all reported strains are proposed to be initiated by hydroxylation on a C atom adjacent to the amine group by cytochrome P450 monooxygenases, thereby forming unstable compounds A novel piperidine degradation mechanism in a newly isolated piperidine degrader Pseudomonas sp.…”