Lubrication and oil recovery by biosurfactant produced by Acinetobacter johnsonii ABR6

Solid and semi-solid wastes are produced as oil sludge at different stages of crude oil refining. Accumulation of oil waste in the refinery reduces the efficiency of oil refining and its release causes environmental pollution.  The purpose of this study is to lubricate crude oil in pipelines and recycle oil using a biosurfactant produced by an indigenous strain.   The biosurfactant-producing isolates were obtained from petroleum reservoir in Isfahan Oil Refinery, Isfahan, Iran. Screening was performed by oil displacement method. Also the surface tension was measured by tensiometer. Biosurfactant chemical structure was identified by using chemical analysis. Oil recovery from the sludge was measured under controlled condition. The effect of biosurfactant lubrication was investigated on crude oil in the pipelines in vitro. The stability of biosurfactant in different environmental conditions was also determined. The best biosurfactant-producing bacterium was identified as Acinetobacter johnsonii ABR6, and its 16S-rDNA genomic sequence was deposited in GenBank under the accession number of MK100470. Chemical analysis of TLC and FTIR confirmed that the produced biosurfactant was lipopeptide. The biosurfactant obtained from this bacterium recovered 50% of crude oil from petroleum sludge and also reduced transportation speed from 64 to 35 seconds. This biosurfactant had high stability in 5% w/v NaCl, pH range of 8 to 10, temperature of 60°C and autoclave conditions.   The results of this study showed that the biosurfactant produced by the native strain of Acinetobacter Johnson ABR6, in addition to operating in extreme conditions, also has the ability to recover oil and increase the transfer rate of crude oil in pipelines. Therefore, the use of this biosurfactant can be considered as an asset in the petroleum industry