M. Labidi et al., Biotransformation and partial mineralization of the explosive 2,4,6-trinitrotoluene (TNT) by rhizobia, CAN J MICRO, 47(6), 2001, pp. 559-566
Three strains, T10, B5, and M8, each belonging to a different species of th
e family Rhizobiaceae and isolated from atrazine-contaminated soils, were t
ested for their ability to transform 2,4,6-trinitrotoluene (TNT) (50 mug.mL
(-1)) in liquid cultures using glucose as the C-source. All three strains w
ere able to transform TNT to hydroxy lamino dinitro toluenes (2-HADNT, 4-HA
DNT), aminodinitrotoluenes (2-ADNT, 4-ADNT), and diaminonitrotoluene (2,4-D
ANT). The transformation was significantly faster in the presence of glutam
ate. Furthermore, the major metabolites that accumulated in cultures were 2
-ADNT with glucose, and 4-ADNT with glutamate plus glucose. Rhizobium trifo
lii T10 was also tested for its ability to transform high levels of TNT (si
milar to 350 mug.mL(-1)) in a soil slurry. Almost 60% of the TNT was transf
ormed within 2 days in bioaugmented soil slurries, and up to 90% when cultu
res were supplemented with glucose and glutamate. However, mineralization w
as minimal in all cases, less than 2% in 78 days. This is the first report
on the degradation of TNT by rhizobial strains, and our findings suggest th
at rhizobia have the potential to play an important role in the safe decont
amination of soils and sites contaminated with TNT if bioaugmentation with
rhizobia is shown to have no ecotoxicological consequence.