ABSTRACT
In a process for cleaning hydrocarbonaceous residues, including residual petroleum from laboratory made oil-contaminated vessels, several previously isolated bacteria from Ilam and Paydar oil reservoirs, were used. The isolated strains were compared with the standard sample of Acinetobacter calcoaceticus PTCC 1318 from Persian Type Culture Collection [PTCC]. This gram-negative bacterium grows on a variety of different substrates as sole carbon and energy sources, including crude oil, soy oil and ethanol. It is oxidase-negative, non-motile and strictly aerobic. Among the isolated strains, two autochthonous strains were found to produce an extracellular emulsifying agent when grown in Mineral Salt Medium containing soy oil, ethanol or local crude oil. The crude emulsifier of PTCC1318, Paydar-4 and Ilam-1 were concentrated from the cell-free culture fluid by ammonium sulfate precipitation to yield 1.89 g, 1.78 g and 1.69 g of bioemulsan, respectively. Although measuring the surface tension [ST] is not very applicable procedure in case of bioemulsan, but in order to prove this theory, ST was conducted.Further analysis of purified emulsion was performed to prove the molecular structure by Carbon13 Nuclear Magnetic Resonance, Proton1Nuclear Magnetic Resonance and Fourier Transform Infrared Radiation methods. These investigations showed that the molecular weight of emulsion produced by species isolated from Ilam and Paydar crude oil reservoirs are comparable with Acinetobacter calcoaceticus PTCC 1318
ABSTRACT
Growth of previously isolated bacteria from Iranian oil reservoirs on different carbon and energy sources and under varying conditions have been used to produce a class of extracellular microbial protein-associated lipopolysaccharides named emulsan.Several Bacteria were previously isolated from Iranian oil reservoirs and designated as; Ilam-1 and Paydar-4. In present study, the isolated strains were compared with standard sample of Acinetobacter calcoaceticus RAG-1 from Persian Type Culture Collection [PTCC 1641], IROST. Among the isolated strains, two strains were found to produce an extracellular, emulsifying agent when grown in Mineral Salt Medium containing soya oil, ethanol or local crude oil. The isolated bacteria were cultured and further analysed using protein estimation, reducing sugar analysis, hemolytic activity, surface tension and emulsification activity tests. The crude emulsifier of RAG-1, PAYDAR-4 and ILAM-1 were concentrated from the cell-free culture fluid by ammonium sulfate precipitation to yield 1.89g, 1.78g and 1.69g of bioemulsan respectively. Emulsifying activity was observed over the entire production process. These investigations showed that emulsan produced by isolated Iranian crude oil reservoir were comparable with Acinetobacter calcoaceticus RAG-1 which is made of carbohydrate backbone as its hydrophilic part [N-acetyl-D-galactoseamine, N-acetylgalactoseamine uronic acid, diamino-6-deoxy-D-glucose] and fatty acid chain as its hydrophobic portion