Chemically modified surface functional groups of Alcaligenes sp. S-XJ-1 to enhance its demulsifying capability
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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.
KeywordsDemulsifying bacteria Chemical modification Amino group Carboxyl group
This work was supported by the National Natural Science Foundation of China (51478325 and 51608375) and China Postdoctoral Science Foundation (2016M591711).
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Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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