J. Hawari et al., Biotransformation of 2,4,6-trinitrotoluene with Phanerochaete chrysosporium in agitated cultures at pH 4.5, APPL ENVIR, 65(7), 1999, pp. 2977-2986
The biotransformation of 2,4,6-trinitrotoluene (TNT) (175 mu M) by Phaneroc
haete chrysosporium with molasses and citric acid at pH 4.5 was studied. In
less than 2 weeks, TNT disappeared completely, but mineralization (liberat
ed (CO2)-C-14) did not exceed 1%. A time study revealed the presence of sev
eral intermediates, marked by the initial formation of two monohydroxylamin
odinitrotoluenes (2- and 4-HADNT) followed by their successive transformati
on to several other products, including monoaminodinitrotoluenes (ADNT). A
group of nine acylated intermediates were also detected. They included 2-N-
acetylamido-4,6-dinitrotoluene and its p isomer, 2-formylamido-4,6-dinitrot
oluene and its p isomer (as acylated ADNT), 4-N-acetylamino-2-amino-6-nitro
toluene and 4-N-formylamido-2-amino-6-nitrotoluene (as acetylated DANT), 4
N-acetylhydroxy-2,6-dinitrotoluene and 4-N-acetoxy-2,6-dinitrotoluene (as a
cetylated HADNT), and finally 4-N-acetylamido-2-hydroxylamino-6-nitrotoluen
e. Furthermore, a fraction of HADNTs were found to rearrange to their corre
sponding phenolamines (Bamberger rearrangement), while another group dimeri
zed to azoxytoluenes which in turn transformed to azo compounds and eventua
lly to the corresponding hydrate derivatives. After 30 days, all of these m
etabolites, except traces of 4-ADNT and the hydrate derivatives, disappeare
d, but mineralization did not exceed 10% even after the incubation period w
as increased to 120 days. The biotransformation of TNT was accompanied by t
he appearance of manganese peroxidase (MnP) and lignin-dependent peroxidase
(LiP) activities. MnP activity was observed almost immediately after TNT d
isappearance, which was the period marked by the appearance of the initial
metabolites (HADNT and ADNT), whereas the Lip activity was observed after 8
days of incubation, corresponding to the appearance of the acyl derivative
s. Both MnP and LiP activities reached their maximum levels (100 and 10 U/l
iter, respectively) within 10 to 15 days after inoculation.