Metabolic pathway of xenoestrogenic short ethoxy chain-nonylphenol to nonylphenol by aerobic bacteria, Ensifer sp. strain AS08 and Pseudomonas sp. strain AS90

Ensifer sp. strain AS08 and Pseudomonas sp. strain AS90 degrading short ethoxy (EO) chain-nonylphenol (NP) [NPEO_av2.0 containing NP mono- ∼ tetraethoxylates (NP1EO ∼ NP4EO); average 2.0 EO units] were isolated by enrichment cultures. Both strains grew on NP but not on octyl- and nonylphenol polyethoxylates (NPEOs) (average 10 EO units). Growth and degradation of NPEO_av2.0 was increased with increased concentrations of yeast extract (0.02–0.5%) in a culture medium. Culture supernatants of both strains grown on NPEO_av2.0 were analyzed by high-performance liquid chromatography, showing degradation of NP4EO–NP1EO. The metabolites from nonylphenol diethoxylate (NP2EO) by resting cells of both strains were identified by gas chromatography–mass spectrometry as nonylphenoxyethoxyacetic acid, NP1EO, nonylphenoxyacetic acid (NP1EC), and NP, while those from NP1EO were identified as NP1EC and NP. Cell-free extracts from strain AS08 grown on NPEO_av2.0 dehydrogenated NPEOs, NPEO_av2.0, NP2EO, NP1EO, and PEG 400, but the extracts were inactive toward di- ∼ tetraethylene glycol. Aldehydes were formed in the reaction mixture of each substrate with cell-free extracts. From these results, the aerobic metabolic pathway for short EO chain-NP is proposed: A terminal alcohol group of the EO chain is oxidized to a carboxylic acid via an aldehyde, and then one EO unit is removed. This process is repeated until NP is produced.English edition: The paper was edited by a native speaker through KN international ()