Degradation of morpholine and thiomorpholine by an environmental Mycobacterium involves a cytochrome P450.: Direct evidence of intermediates by in situ 1H NMR

A strain of Mycobacterium sp. RP1 was isolated from a contaminated activated sludge. It was capable of utilizing morpholine, a waste of chemical industry, as sole source of carbon, nitrogen and energy. The kinetic of biodegradation of morpholine was followed directly on the incubation medium using in situ H-1 NMR. This technic allowed to identify two intermediates of the degradative pathway: glycolate and 2-(2-aminoethoxy)acetate. The inhibitory effects of metyrapone on the degradative abilities of the strain RP1 indicated the involvement of a cytochrome P450. This observation was confirmed by spectrophotometric analysis and H-1 NMR. Metyrapol, a known metabolite of metyrapone, was also found to be an inhibitor. The same study of degradation of thiomorpholine showed the formation of sulfoxide, which confirmed the presence of a cytochrome P450. (C) 1998 Elsevier Science B.V. All rights reserved.