Demulsification capabilities of a Microbacterium species for breaking water-in-crude oil emulsions

A bacterium strain belonging to Microbacterium sp., isolated from oily sludge samples of Siri Island in the south of Iran, produced a strong, thermo stable microbial demulsifier (Y x/s =0.663, Y p/s =0.204, productivity=0.185 g L -1 h -1 ) on glucose as a sole carbon source supplemented with yeast extract. The optimum values of temperature, inoculum concentration, pH and culture age for microbial demulsifier production were 25°C, 10 8 CFU mL -1 , 7 and 24 h, respectively. The maximum demulsification activity and the half-life value (t 1/2 ) of culture broth measured for a water-in-crude oil (W/CO) emulsion were 96.4% and 36 h at 80°C in flask. The demulsifier was purified to homogeneity using cold ethanol. For 4.33 mg mL -1 of partially purified microbial demulsifier, the half-life value for the W/CO model emulsion was 3 h. Keywords : Biopolymer, demulsification, Microbacterium , demulsifier, petroleum emulsion, water-in-crude oil African Journal of Biotechnology Vol. 12(16), pp. 2019-2026