Cleaning oil-contaminated vessel by emulsan producers [autochthonous bacteria]

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