title: Chemically modified surface functional groups of Alcaligenes sp. S-XJ-1 to enhance its demulsifying capability.
abstract: Cell-surface functional groups (amino, carboxyl, hydroxyl, as well as phosphate) were chemically modified in various ways to enhance the demulsification capability of the demulsifying bacteria Alcaligenes sp. S-XJ-1. Results demonstrated that the demulsifying activity was significantly inhibited by amino enrichment with cetyl trimethyl ammonium bromide, amino methylation, hydroxyl acetylation, and phosphate esterification, but was gradually promoted by carboxyl blocking with increasing the extents of esterification. Compared with the raw biomass, an optimal esterification of carboxyl moieties enhanced the demulsification ratio by 26.5% and shortened the emulsion half-life from 24 to 8.8 h. The demulsification boost was found to be dominated by strengthened hydrophobicity (from 53° to 74°) and weakened electronegativity (from -34.6 to -4.3 mV at pH 7.0) of the cell surface, allowing the rapid dispersion and adsorption of cells onto the oil-water interface. The chemical modification of the functional groups on the biomass surface is a promising tool for the creation of a high-performance bacterial demulsifier.
authors.affiliation: College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Ministry of Education, Key Laboratory of Yangtze River Water Environment, Tongji University, Shanghai, 200092, China.
authors.forename: Yuyan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Ministry of Education, Key Laboratory of Yangtze River Water Environment, Tongji University, Shanghai, 200092, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.affiliation: College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Ministry of Education, Key Laboratory of Yangtze River Water Environment, Tongji University, Shanghai, 200092, China.
authors.forename: Xiangfeng
authors.initials: X
authors.lastname: Huang
authors.affiliation: College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Ministry of Education, Key Laboratory of Yangtze River Water Environment, Tongji University, Shanghai, 200092, China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Lu
authors.affiliation: Post-Doctoral Research Station, Tongji University, Shanghai, 200092, China. kai878@sina.com.
authors.forename: Kaiming
authors.identifier: http://orcid.org/0000-0003-0633-1364
authors.initials: K
authors.lastname: Peng
mesh_terms: D000421:Alcaligenes / Q000737:chemistry* / Q000254:growth & development / Q000378:metabolism*; D018533:Biomass; D004655:Emulsions; D057927:Hydrophobic and Hydrophilic Interactions; D013499:Surface Properties; D013501:Surface-Active Agents / Q000378:metabolism
chemical_list: D004655:Emulsions; D013501:Surface-Active Agents
keywords: Amino group; Carboxyl group; Chemical modification; Demulsifying bacteria