In vitro anaerobic trinitrotoluene (TNT) degradation with rumen fluid ...

1.3 TNT degradation under anaerobic conditions
The degradation of explosives under anaerobic conditions has been intensively
studied within past the few years. Various microorganisms, including denitrifing,
sulfate reducing, methanogenic, and specific enzymes, were applied to examine the
feasibility of explosives degradation under anaerobic conditions. Principal findings are
as summarized below.
McCormick et al. (18) investigated TNT reduction by cell-free extracts, resting
cells, and growing cultures. The cell-free extracts and resting cells reduced three nitro
groups to corresponding amino groups under strctly anaerobic conditions. Growing
cultures of V. alkalescens and E. colt produced 2,4DA6NT. In the case of
nitrotoluene, the reduction of a para-positioned nitro group was followed by the
ortho-positioned group. The nitro reductase separated from V. alkalescens consisted
of hydrogenase and ferredoxin-like materials, but whether the nitro reduction took
place solely via hydrogenase or ferredoxin was not conclusively demonstrated.
Boopathy et al. (5) examined the anaerobic removal of TNT under different
electron accepting conditions in a soil-bacterial consortium. Under nitrate reducing
conditions, 82% of the TNT was removed from contaminants with 100 ppm of TNT.
Under sulfate reducing conditions, 30% of 100 ppm was removed. Using CO2 as an
electron acceptor, 35 % of 100 ppm TNT was removed. In these experiments, TNT
did not serve as a carbon or primarily energy source, but its removal was achieved by
co-metabolism with the energy source. The TNT intermediate reductions were
4A26DNT and 2A46DNT, wherein the former was predominant.
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