LAUSR

Kazakhstan is one of the largest oil producers in the world. But, at present, the most oil fields of country have entered to the final stage of development, which characterized by drop in production rates. A promising way to increase the oil recovery from depleted oil reservoirs by ecologically friendly method is the use of microorganisms with high metabolic activity. The aim of our work is screening biosurfactant producing bacteria for application in microbial enhanced oil recovery. The screening of biosurfactant producing bacteria was carried out by determining the emulsifying activity of isolates and quantitative determination of produced biosurfactants by spectrophotometric method. Interfacial tension between crude oil and biosurfactant solution was determined using the ring detachment method. Active bacterial isolates were identified based on morphological and 16S rDNA sequence analysis. From 4 oil reservoirs of west Kazakhstan on different nutrient media 35 bacterial isolates were isolated. Among them 4 bacteria posessed the greatest emulsifying activity – more than 70%. Isolate Zh 105-9 produced the largest amount of biosurfactants (more than 10 mg/l). Interfacial tension between crude oil and biosurfactant solution produced by strain Zh 105-9 reduced to 38.6 mN/m. This strain was identified as Bacillus sp.