Bacterial biodegradation of glycerol trinitrate

Glycerol trinitrate (GTN) is widely used as a high explosive and as a potent vasodilator in the treatment of heart diseases including angina pectoris. Its sensitivity to detonation by mechanical shock, and its pharmacological potency, while critical to its utility, also constitute problems for handling and treating wastes arising from the production and use of the compound. This paper describes bacterial biodegradation of GTN, which may offer a means of removal of GTN from waste streams and bioremediation of contaminated land sites. Pseudomonas sp. strain RI-NG1 was isolated from river sediment by enrichment culture on minimal salts/glycerol/GTN medium. Batch culture experiments established that this isolate utilised GTN as its sole source of nitrogen. Analysis of the growth medium using HPLC showed the presence of glycerol dinitrates and glycerol mononitrates. Isomeric glycerol 1,2-dinitrate and glycerol 1,3-dinitrate were produced simultaneously and concomitantly with the disappearance of GTN, with significant regioselectivity for the production of the 1,3-isomer. After GTN disappearance was complete, the dinitrates were further degraded to glycerol 1- and 2-mononitrates. Preliminary experiments indicated that the nitro group was liberated as nitrite, not nitrate. The bacterial biodegradation of GTN thus shows parallels with GTN metabolism in eukaryotic (mammalian and fungal) systems.