Figure 1.
Growth characterization of Rhodococcus sp. strain MB-P1 on 2-C-4-NA as the sole carbon, nitrogen, and energy source.
(•), 2-C-4-NA; (▴), NO2−; (Δ), NH4−; (○), Cl−; (▪), total protein. Values are presented as arithmetic means of data obtained from experiments carried out in triplicates; error bars represent standard deviation.
Figure 2.
Degradation kinetics of 2-C-4-NA and 4-A-3-CP during resting cell studies performed by 2-C-4-NA-induced cells of strain MB-P1.
(A) 2-C-4-NA degradation kinetics. (•), 2-C-4-NA; (▪), 4-A-3-CP; (Δ), 6-CHQ; (○), 2-C-4-NA in abiotic control. (B) 4-A-3-CP degradation kinetics. (•), 4-A-3-CP; (Δ), 6-CHQ. Values are presented as arithmetic means of data obtained from experiments carried out in triplicates; error bars represent standard deviation.
Figure 3.
Representative HPLC and GC-MS chromtograms along with mass spectra of metabolites identified during the degradation of 2-C-4-NA by resting cells of Rhodococcus sp. strain MB-P1.
(A) HPLC chromatograms of metabolites identified at different time intervals. Peak at Rt value of 8.5 min corresponds to 2-C-4-NA; Peak at Rt value of 4.86 min corresponds to 4-A-3-CP; Peak at Rt value of 3.28 min corresponds to 6-CHQ. (B) GC-MS chromatogram of the authentic standards and the identified metabolites. Peak at Rt value of 6.41 min corresponds to 2-C-4-NA; Peak at Rt value of 7.62 min corresponds to 4-A-3-CP; Peak at Rt value of 9.52 min corresponds to 6-CHQ. (C) Mass spectra of metabolites (Left side; 4-A-3-CP and right side; 6-CHQ) of 2-C-4-NA as analyzed by GC-MS.
Table 1.
Determination of aniline dioxygenase activity in strain MB-P1 measured by oxygen uptake by 2-C-4NA-grown versus 1/4-NB-grown cellsa.
Figure 4.
Ring cleavage inhibition studies using 2, 2-dipyridyl.
(A) Treated with 2, 2-dipyridyl. (B) Untreated with 2, 2-dipyridyl. 2-C-4-NA (•); 4-A-3-CP (▴); and 6-CHQ (○).Values are presented as arithmetic means of data obtained from experiments carried out in triplicates; error bars represent standard deviation.
Figure 5.
Proposed metabolic pathway for aerobic degradation of 2-C-4-NA by Rhodococcus sp. strain MB-P1.
According to the results obtained presented here, 4-A-3-CP and 6-CHQ are identified as major intermediates during degradation of 2-C-4-NA.