Characterization of Two Novel Propachlor Degradation Pathways in Two Species of Soil Bacteria

Abstract

Propachlor (2-chloro-N-isopropylacetanilide) is an acetamide herbicide used in preemergence. In this study, we isolated and characterized a soil bacterium, Acinetobacter strain BEM2, that was able to utilize this herbicide as the sole and limiting carbon source. Identification of the intermediates of propachlor degradation by this strain and characterization of new metabolites in the degradation of propachlor by a previously reported strain ofPseudomonas (PEM1) support two different propachlor degradation pathways. Washed-cell suspensions of strain PEM1 with propachlor accumulated N-isopropylacetanilide, acetanilide, acetamide, and catechol. Pseudomonas strain PEM1 grew on propachlor with a generation time of 3.4 h and aKs of 0.17 ± 0.04 mM.Acinetobacter strain BEM2 grew on propachlor with a generation time of 3.1 h and a Ks of 0.3 ± 0.07 mM. Incubations with strain BEM2 resulted in accumulation of N-isopropylacetanilide,N-isopropylaniline, isopropylamine, and catechol. Both degradative pathways were inducible, and the principal product of the carbon atoms in the propachlor ring was carbon dioxide. These results and biodegradation experiments with the identified metabolites indicate that metabolism of propachlor by Pseudomonas sp. strain PEM1 proceeds through a different pathway from metabolism byAcinetobacter sp. strain BEM2.

Anaerobic Transformation of the Iodinated X-ray Contrast Medium Iopromide, Its Aerobic Transformation Products, and Transfer to Further Iodinated X-ray Contrast Media

“…Direct hydrolysis of the tertiary amide in chain A of DAMI is contrary to the results of Helbling et al, who observed an N-dealkylation as the initial reaction in the transformation pathway of tertiary amides under aerobic conditions. In contrast, in two pure culture studies, the tertiary amides of DEET ( N , N -diethyl m -toluamide) and propachlor were also found to be transformed by direct hydrolysis. , No N-dealkylated intermediate TP of DAMI was detected in the batch experiments in this study. However, it cannot be completely excluded that N-dealkylation was the first step in the transformation of the tertiary amide and that subsequent hydrolysis of the resulting secondary amide was considerably faster than the initial N-dealkylation.…”

Production, characterization, and applications of bioemulsifiers (BE) and biosurfactants (BS) produced by Acinetobacter spp.: A review

“…Because of this, the apparent solubility of PAH is enhanced up to 20‐fold, which is followed by significant increase in biodegradation rate of PAH. It is reported that pure AlnA can also effectively emulsify wide range of other hydrophobic compounds, such as long chain alkanes, aromatics, paraffin, and crude oil .…”

Structure-Based Interpretation of Biotransformation Pathways of Amide-Containing Compounds in Sludge-Seeded Bioreactors

“…Many pharmaceuticals and other xenobiotics whose fate is through WWTPs contain amide groups (see ref for a review of xenobiotics that have been identified in WWTPs). Data in the literature further suggest that amides may either be hydrolyzed or N-dealkylated during biotransformation, but the structural features that may promote or inhibit either biotransformation reaction remain unknown. Accordingly, the UM-PPS contains transformation rules for hydrolysis and N-dealkylation which are both triggered by secondary and tertiary amide substructures.…”