N-Methylmorpholine-N-oxide Pathway Map

N-Methylmorpholine-N-oxide (MMO) is a common industrial solvent used in the production of cellulose fibers. Currently, it is the only such compound known that has the ability to solvate cellulose for downstream utilization in fiber production (Meister et al., 1998). It is an integral component of the Lyocell process used for such previously mentioned purposes (Konkin et al., 2008). The highly polar nature of MMO provides an excellent solvent for disruption of the extensive hydrogen-bonded network formed by carbohydrate polymers (Kuo et al., 2009). MMO has also been shown to be useful in the production of biofuels; pretreatment of cellulosic biomass such as sugarcane with the compound was shown to increase the degree of downstream enzymatic hydrolysis for improved yields following fermentation (Konkin et al., 2008).

Until the discovery of certain microbial species that contain the machinery to metabolize N-methylmorpholine-N-oxide, this compound was thought to be environmentally persistent (Meister et al., 1998). Strains of E. coli have the ability to initiate the biotransformation of MMO to N-methylmorpholine (Iobbi-Nivol et al., 1996). Subsequent conversion to morpholine then enables its complete metabolism by strains of Mycobacterium via glycolate-ethanolamine pathways (Sielaff et al., 2001 and Schrader et al., 2000).

The following is a text-format N-methylmorpholine-N-oxide pathway map. An organism which can initiate the pathway is given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (4k) format.

         N-Methylmorpholine-N-oxide      
 	          E. coli       
                     |
                     | 
                     | trimethylamine-N-oxide
                     | reductase 
                     | 
                     |		
                     v                               
            N-Methylmorpholine      
                     |
                     | trimethylamine
                     | dehydrogenase   
                     |
                     +----------------------------+               
                     |                            |               
                     v                            v 
                Morpholine                   Formaldehyde
                     |                            |
                     |                            |
                     |                            |
                     |                            |
                     v                            v
		   to the		     Intermediary		
	         Morpholine 	              Metabolism 
		  Pathway 			(KEGG)    

Page Author(s): Lee A. Meier and Michael Turnbull

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http://eawag-bbd.ethz.ch/mmo/mmo_map.html