Cell surface properties of the demulsifying strain Alcaligenes sp. S-XJ-1 governing its behavior in oil–water biphasic systems

Abstract

Bacterial behavior in oil–water biphasic systems plays an essential role in hydrophobic contaminant degradation, oil recovery, and emulsion breaking. Less is known about the cell surface properties that govern their behaviors in oil–water biphasic systems. In this study, biphasic partitioning and aggregation of a demulsifying strain of Alcaligenes sp. S-XJ-1 were experimentally measured and evaluated based on the cell surface properties of surface charge, surface free energy, and cell surface hydrophobicity (CSH). The S-XJ-1 was cultivated with five different carbon sources, and the results showed a highly varied partitioning, aggregation behavior, and cell surface properties. The calculated interaction energies, based on the cell surface properties, were consistent with the results of their behavior. Among the cell surface properties, the electron-donor character (γ⁻, range 8.8–57.0 mJ/m²), which correlated well with CSH (ΔG_bwb), was an essential indicator of cell behavior. A low γ⁻ value enhanced the cell–interface and cell–cell interaction energies, which promoted cell partitioning and aggregation eventually leading to demulsification. The results and analysis provide important information for researchers concerned with cell–cell and cell–interface interactions.

Keywords:

• Cell surface property
• bacterial behavior
• cell biphasic partitioning
• cell aggregation
• demulsifying strain

Funding

This work was supported by the National Natural Science Foundation of China [grant number 51478325], [grant number 51108333].

Disclosure statement

No potential conflict of interest was reported by the authors.