Enantioselective Catabolism of Napropamide Chiral Enantiomers in Sphingobium sp. A1 and B2

Abstract

Napropamide [N,N-diethyl-2-(1-naphthalenyloxy)­propenamide, NAP] is a highly efficient and broad-spectrum amide herbicide. Little is known about the bacterial catabolism of its different enantiomers. Here, we report the isolation of two NAP-degrading strains of Sphingobium sp., A1 and B2, and the different catabolic pathways of different enantiomers in these two strains. Strain A1 dioxygenated NAP at different positions of the naphthalene ring of different enantiomers, leading to the complete degradation of R-NAP while producing a dead-end product from S-NAP. Strain B2 cleaved the amido bonds of both enantiomers, but only the product from S-NAP could be further transformed to form α-naphthol and mineralize in strain B2. The degradation rates of R-NAP and S-NAP in the combination degradation by strains A1 and B2 were 24.8 and 7.5 times that in the single-strain degradation by strain B2 or A1, respectively, showing enhanced synergistic catabolism between strains A1 and B2. This study provides new insights into the enantioselective catabolic network of the chiral herbicide NAP in microorganisms.

Enantioselective Uptake Determines Degradation Selectivity of Chiral Profenofos in Cupriavidus nantongensis X1T

“…The absolute configuration of enantiomers was detected and analyzed with an electronic circular dichroism (ECD) spectrometer as previously reported. 25 The metabolites of profenofos were identified on the basis of the comparison of the retention time and mass spectra to those of standard substances. The mass spectra were obtained with Acquity UPLC−MS/MS (Waters Corp.) as described previously.…”

“…The separated enantiomers of profenofos were collected individually. The absolute configuration of enantiomers was detected and analyzed with an electronic circular dichroism (ECD) spectrometer as previously reported …”

Coinducible Catabolism of 1-Naphthol via Synergistic Regulation of the Initial Hydroxylase Genes in Sphingobium sp. Strain B2

“…1-Naphthol was very slowly degraded in MSM (without other carbon sources) by strain B2, and no cell growth of strain B2 was observed. However, the catabolism of 1-naphthol by strain B2 was greatly enhanced when glucose was also added (7), which is similar to the phenomenon of cometabolism. In this study, the roles of the obligately coexisting primary carbon sources in the enhanced catabolism of 1-naphthol in strain B2 were revealed.…”

“…1-Naphthol is an important raw material for the organic synthesis of pharmaceuticals, pesticides, and dyestuffs (4,5) and is also the major intermediate during the degradation of carbaryl (6), napropamide (7,8), and polycyclic aromatic hydrocarbons (PAHs) (9). Because of its common use, 1-naphthol is frequently detected in soil, water, and even the ocean (10,11).…”

“…strain B2 (see Fig. S1A in the supplemental material), when (S)-NAP was added as the sole carbon source in minimal salt medium (MSM) (7,8). 1-Naphthol was very slowly degraded in MSM (without other carbon sources) by strain B2, and no cell growth of strain B2 was observed.…”