Complete denitration of nitroglycerin by bacteria isolated from a washwater soakaway

Four axenic bacterial species capable of biodegrading nitroglycerin (glycer ol trinitrate [GTN]) were isolated from soil samples taken from a washwater soakaway at a disused GTN manufacturing plant. The isolates were identifie d by 16S rRNA gene sequence homology as Pseudomonas putida, an Arthrobacter species, a Klebsiella species, and a Rhodococcus species, Each of the isol ates utilized GTN as its sole nitrogen source and removed nitro groups sequ entially from GTN to produce glycerol dinitrates and mononitrates (GMN), wi th the exception of the Athrobacter strain, which achieved removal of only the first nitro group within the time course of the experiment. The Klebsie lla strain exhibited a distinct preference for removal of the central nitro group from GTN, while the other Eve strains exhibited no such regioselecti vity. All strains which removed a second nitro group from glycerol 1,2-dini trate showed regiospecific removal of the end nitro group, thereby producin g glycerol 2-mononitrate. Most significant was the finding that the Rhodoco ccus species was capable of removing the final nitro group from GMN and thu s achieved complete biodegradation of GTN, Such complete denitration of GTN has previously been shown only in mixed bacterial populations and in cultu res of Penicillium corylophilum Dierckx supplemented with an additional car bon and nitrogen source. Hence, to the best of our knowledge, this is the f irst report of a microorganism that can achieve complete denitration of GTN .