Introducing biodemulsifier producing bacteria isolated from oil contaminated soils and measuring their performance in separating water from oil

Biodemulsifiers are a group of biosurfactants with emulsion breaking ability and their most important application is separation of water from crude oil. These compounds can be a good substitute for chemical demulsifiers, due to their biocompatibility. The aim of this study was to isolate biodemulsifier producing bacteria and evaluate their performance in demulsifying water in oil emulsions. For this purpose, after sampling, bacterial isolation was made in modified mineral salt medium and purified on Mueller-Hinton agar. The production of biosurfactant was evaluated through hemolytic activity assay, drop collapse test, oil spreading test and cell hydrophobicity measurements based on microbial adhesion to hydrocarbons. The biodemulsifier activity of these compounds and their position in the cells were investigated by examining the demulsification ratio of water in kerosene emulsions in demulsification tests. Based on staining and biochemical and enzymatic tests, these isolates were identified as Bacillus sp. HS9, Staphylococcus sp. HS10, Bacillus sp. HS11, Bacillus sp. HS12. The demulsification activity of these isolates in breaking water in kerosene emulsions were 25 ± 3, 28.5 ± 5, 27.14 ± 1, 51.57 ± 1 percent, respectively. Among these isolates, Bacillus sp. HS12 with 51.57 ± 1 percentage of demulsification activity was selected as the preferred isolate. With regard to demulsification potential of these isolates, it is suggested that their performance be evaluated in crude petroleum and desalting units conditions in order to be applied in enhanced oil recovery and breaking undesirable emulsions in upstream facilities.