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

Abstract

A bacterium strain belonging to Microbacterium sp., isolated from oily sludge samples of Siri Island in\rthe south of Iran, produced a strong, thermo stable microbial demulsifier (Yx/s=0.663, Yp/s=0.204,\rproductivity=0.185 g L-1 h\r-1\r) on glucose as a sole carbon source supplemented with yeast extract. The\roptimum values of temperature, inoculum concentration, pH and culture age for microbial demulsifier\rproduction were 25°C, 108 CFU mL-1\r, 7 and 24 h, respectively. The maximum demulsification activity and\rthe half-life value (t1/2) of culture broth measured for a water-in-crude oil (W/CO) emulsion were 96.4%\rand 36 h at 80°C in flask. The demulsifier was purified to homogeneity using cold ethanol. For 4.33 mg\rmL-1\rof partially purified microbial demulsifier, the half-life value for the W/CO model emulsion was 3 h.