[Extraction of surface active substance and analysis of demulsifying characteristics for the demulsifying strain Alcaligenes sp. S-XJ-1].

Extraction and identification of surface active substance of Alcaligenes sp. S-XJ-1, as well as description of its emulsion breaking process were conducted to reveal the demulsifying characteristics of this demulsifying strain. Alkali solvent was adopted in the extraction process with conditions optimized as 35 degrees C, 0.08 mol x L(-1) of alkali concentration, 12 g x L(-1) of sample to solution ratio, and 4 h of extraction time by launching both single-factor and orthogonal tests. Under this optimal condition, the extracted surface active substance (the extraction ratio was 36.1%) achieved 77% emulsion breaking ratio for 500 mg x L(-1) within 48 h. FT-IR showed the existence of glycolipids, lipids and proteins in the surface active substance, the molecular weight of which mainly scattered between 55 and 61 256. Saccharides, lipids and proteins were identified as the three chief components in surface active substance with the content of 22.2%, 7.5% and 13.4%, respectively. The proteins were further proved to take the most responsibility for the emulsion breaking ability. Moreover, obvious difference in the emulsion breaking process was demonstrated between the original demulsifying strain S-XJ-1 and the extracted surface active substance by real time observation of Turbiscan Lab Expert. The results suggested that the demulsifying efficiency of the strain was jointly contributed by its surface active substance and demulsifying cell morphology, and the former possessed higher functional priority than the latter.