Uptake mechanism of di-n-butyl phthalate by Novosphingobium species DNB-S3

Phthalate esters (PAEs) in the environment are mainly reported to be removed through the biochemical degradation by microorganisms . However, the adsorption of DBP is the initial process of using it as a carbon source. In this process, little is known about changes in cell surface properties at the subcellular level of degrading bacteria. In our work, Novosphingobium species DNB-S3 was found to be an efficient DBP-degrading bacterium with 95% DBP removal in 72 h at an initial concentration of 500 mg L −1 . In soil simulation experiment, the initial concentration of DBP decreased from 25 mg kg −1 to 1.9 mg kg −1 after the inoculation of DNB-S3. In addition, DNB-S3 also showed degradation capability on other PAEs. DNB-S3 was cultured under four treatment conditions with different carbon sources, namely MSM-DBP, MSM-GLU, MSM-DBP + GLU, and LB. The cell surface hydrophobicity , functional groups on cell surface and morphological changes of DNB-S3 were further investigated. Morphological studies showed that the presence of DBP induced the disappearance of microcapsule on DNB-S3. Infrared spectroscopy and Raman spectra of DNB-S3 surface showed that the lipid-containing groups on the outer membrane were externally exposed from cellular structure, resulting in an increase of cell surface hydrophobicity (CSH). Eventually, the high CSH indicates that DNB-S3 has an efficient ability of DBP uptake. Our research adds an interesting dimension to the degradation study of bacterially mediated organic pollutants and the uptake mechanisms of hydrocarbons.