Figure 1.
Biotransformation of MNA in soil microcosms under aerobic conditions.
(•), nitrogen-amended; (○), unamended; (▴), carbon-amended; (□), carbon and nitrogen-amended; (▪), sterile. Values are presented as arithmetic mean of data obtained from experiments carried out in triplicate; error bars represent standard deviation.
Figure 2.
Growth characteristics and degradation kinetics of Pseudomonas sp. strain FK357 in carbon-free MSM supplemented with different concentrations of MNA.
(•), 50 µM; (▴), 150 µM, (Δ), 250 µM; (○), 350 µM; (▪), 500 µM; (□), 700 µM. (A) Growth of strain FK357 on different concentrations of MNA. (B) Degradation of MNA at different concentrations by strain FK357.
Figure 3.
Growth of Pseudomonas sp. strain FK357 on MNA as the sole carbon, nitrogen, and energy source.
(•), MNA; (▴), 4-NA; (Δ), NO2−; (▪), total protein; (○), NH4+. Values are presented as arithmetic mean of data obtained from experiments carried out in triplicate; error bars represent standard deviation.
Figure 4.
Mass-fragmentation patterns of the metabolites identified by GC-MS analysis during the degradation of MNA by resting cells of Pseudomonas sp. strain FK357.
(A) Mass-fragmentation patterns of 4-NA (B) Mass-fragmentation patterns of 4-AP, and (C) Mass-fragmentation patterns of BT.
Figure 5.
Kinetics of MNA degradation by MNA-induced and un-induced cells of strain FK357 and identification of MNA degradation intermediates.
(A) Kinetics of MNA degradation. (•), MNA; (○), MNA; (▪), MNA in abiotic control. (B) Identification of MNA degradation intermediates. (○), 4-NA; (▴), 4-AP; (Δ), BT. Values are presented as arithmetic mean of data obtained from experiments carried out in triplicate; error bars represent standard deviation.
Figure 6.
Stoichiometric N-demethylation of MNA and monooxygenation of 4-NA by cell-free lysates prepared from MNA grown cells of strain FK357.
(A) N-demethylation of MNA to 4-NA along with concomitant production of HCHO. (•), MNA; (▾), 4-NA; (○), HCHO. (B) Monooxygenation of 4-NA to 4-AP with stoichiometric release of NO2−. (•), 4-NA; (▾), 4-AP; (○), NO2−. Values are presented as arithmetic mean of data obtained from experiments carried out in triplicate; error bars represent standard deviation.
Table 1.
Oxygen uptake by MNA-grown and 1/4-NB grown cellsa.
Figure 7.
Formation of the maleylacetate (MA) from benzenetriol (BT) by crude cell extracts of Pseudomonas sp. strain FK357.
Sample and reference cuvette contained phosphate buffer (50 mM, pH 7.0), 10 mM Fe (NH4)2(SO4)2.6 H2O, and 0.5 mg ml−1 protein in a 1.0-ml mixture. The reaction was initiated by addition of 70 µM BT and the spectra were recorded every 1 minute after the addition of BT. The arrows indicate the directions of spectral changes.
Figure 8.
Proposed metabolic pathway for aerobic degradation of MNA by Pseudomonas sp. strain FK357.