Ether hydrolase initiates biodegradation of the insensitive explosive, 2,4-dinitroanisole

2,4-Dinitroanisole (DNAN) is an insensitive munitions ingredient used in explosive formulations as a replacement for 2,4,6-trinitrotoluene (TNT). Nocardioides sp. strain JS1661 was isolated from activated sludge based on its ability to grow on DNAN as the sole source of carbon and energy under aerobic conditions. The genome was sequenced and the genes encoding the catabolic pathway were identified. Enzyme assays indicated that the first reaction involves hydrolysis of DNAN to produce stoichiometric amounts of methanol and 2,4-dinitrophenol (2,4-DNP), both of which are biodegradable by a variety of soil bacteria.  The hydrolase is stable and robust in preliminary experiments and the genes that encode its synthesis have been identified and sequenced. The enzyme requires no cofactors and is highly active and robust outside the bacterial cells that produce it, thus there are no obvious constraints to its application in a variety of aqueous systems.  Growth yield and enzyme assays indicated that 2,4-DNP undergoes subsequent degradation in the isolate by a previously established pathway involving formation of a hydride-Meisenheimer complex and release of nitrite. The catabolic pathway seems to have been assembled recently by recruitment of the genes encoding the hydrolase to extend the well- established 2,4-DNP catabolic pathway. The discovery of the enzymes involved in DNAN degradation will provide the basis for the development of DNAN detection and destruction technologies that will be much simpler than current technologies for dealing with TNT.