Saponin-enhanced biomass accumulation and demulsification capability of the demulsifying bacteria Alcaligenes sp. S-XJ-1

Abstract

Surfactants have been widely applied to the bioremediation of hydrophobic organic compound (HOC) contamination. In this study, the biosurfactant saponin was used for improving rape oil utilization to increase the biomass and demulsification capability of the demulsifying bacterial strain Alcaligenes sp. S-XJ-1. A saponin concentration of 0.05%, near its critical micelle concentration, was optimal to enhance biodemulsifier synthesis; the biomass and demulsification ratio increased by 2.4-fold and 18%, respectively. Biomass promotion was revealed to be attributed to the saponin-enhanced utilization of rape oil resulting from improved oil solubilization, cell membrane permeability, and cell activity. The demulsification boost was found to correlate to saponin-strengthened hydrophobicity via an increased protein content and decreased polysaccharide content of the cell-surface. This study advances our understanding of surfactant-enhanced biodemulsifier synthesis with respect to HOC utilization and cell-surface composition responses.