De-emulsification of oil-in-water emulsions by Bacillus subtilis.

Bacillus subtilis grown on glucose produced a de-emulsifier that broke down model oil-in-water emulsions. The deemulsification increased with contact time and the recovery of oil was 98% with 0.6 mg de-emulsifier/ml emulsion. GLC and i.r. analysis of the molecule extracted from cell-free broth demonstrated that the de-emulsifier was acetoin. It may be better to use acetoin, a metabolite of glucose metabolism, to recover oil from oily sludges instead of microbial cells, because of its stability and de-emulsification activity.