AEROBIC GROWTH ON NITROGLYCERIN AS THE SOLE CARBON, NITROGEN, AND ENERGY-SOURCE BY A MIXED BACTERIAL CULTURE

Nitroglycerin (glycerol trinitrate [GTN]), an explosive and vasodilato ry compound, was metabolized by mixed microbial cultures from aeration tank sludge previously exposed to GTN, Aerobic enrichment cultures re moved GTN rapidly in the absence of a supplemental carbon source. Comp lete denitration of GTN, provided as the sole C and N source, was obse rved in aerobic batch cultures and proceeded stepwise via the dinitrat e and mononitrate isomers, with successive steps occurring at lower ra tes. The denitration of all glycerol nitrate esters was found to be co ncomitant, and 1,2-glycerol dinitrate (1,2-GDN) and 2-glycerol mononit rate (2-GMN) were the primary GDN and GMN isomers observed. Denitratio n of GTN resulted in release of primarily nitrite-N, indicating a redu ctive denitration mechanism. Biomass growth at the expense of GTN was verified by optical density and plate count measurements. The kinetics of GTN biotransformation were 10-fold faster than reported for comple te GTN denitration under anaerobic conditions. A maximum specific grow th rate of 0.048 +/- 0.005 h(-1) (mean +/- standard deviation) was est imated for the mixed culture at 25 degrees C, Evidence of GTN toxicity was observed at GTN concentrations above 0.3 mM, To our knowledge, th is is the first report of complete denitration of GTN used as a primar y growth substrate by a bacterial culture under aerobic conditions.