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Efficient breaking of water/oil emulsions by a newly isolated de-emulsifying bacterium, Ochrobactrum anthropi strain RIPI5-1 B Biointerfaces

Mohebali, Ghasemali, Kaytash, Ashk, Etemadi, Narges
Colloids and surfaces 2012 v.98 pp. 120-128
Ochrobactrum anthropi, bacteria, colloids, culture media, emulsions, half life, hydrophobicity, industry, kerosene, oil fields, oils, petroleum, transportation, Iran
Water–oil emulsions occur throughout oil production, transportation, and processing. The breaking of the water/oil emulsion improves oil quality and as a consequence chemically synthesized de-emulsifiers are commonly used in the petroleum industries. Microbial de-emulsifiers represent potential alternatives to the chemicals and may become important products for petroleum industries. The main goal of this work was isolation, identification, and characterization of an efficient de-emulsifying bacterium. Following a multi-step enrichment programme a de-emulsifying bacterium, Ochrobactrum anthropi strain RIPI5-1was isolated from the oil-polluted sandy bank of Siri Island, Iran. The presence of an oil phase in growth medium was found to be unnecessary for production of the de-emulsifier. The de-emulsifying activity of both the whole culture and the cells of this strain was examined using a model multiple water–crude oil (w/o/w) emulsion. This w/o/w emulsion was used for the first time in microbial de-emulsification research. Whole cells of strain RIPI5-1 exhibited high de-emulsifying activity during the late-exponential growth and stationary phases; de-emulsifying activity of the whole culture was highest during the early-exponential growth phase. The time course of de-emulsification by whole culture and whole cells of strain RIPI5-1 was investigated; the initial rate (DeI₁) of breaking of the multiple water–crude oil emulsion by whole culture and whole cells was calculated as 11% and 54%, respectively. However, overall de-emulsification (DeI₈.₅) for whole culture and whole cells was calculated as 63% and 72%, respectively. A clear correlation was observed between cell surface hydrophobicity and the de-emulsifying activity of whole cells. With the water/kerosene emulsion, emulsion half-life (t₁/₂) was found to be <0.5h. The potential activity of this strain was also explained using a complex oilfield emulsion.