The release of petroleum hydrocarbons from a saline-sodic soil by the new biosurfactant-producing strain of Bacillus sp.

Adsorption of old-aged petroleum hydrocarbons to the soil solid phase, which causes biosurfactant loss of performance, is among the limiting factors for the remediation of the saline-sodic soils contaminated with petroleum. Therefore, to find a functional biosurfactant in oil-contaminated saline-sodic soils, the efficiency of 39 bacteria isolated from petroleum-contaminated soils was evaluated. The strains were cultured in the Bushnell–Haas medium, and the produced biosurfactants and bioemulsifiers in this medium were extracted using chloroform/methanol and ethyl acetate extraction methods, respectively. Their partial purification was performed by column chromatography, and eventually, their performance in releasing TPH from the contaminated soil was evaluated. The soil test results revealed that the highest TPH releases due to the effects of the biosurfactants and bioemulsifier produced from SHA302, SH21, and SH72 isolates were 42.4% ± 0.2, 21.6% ± 0.15 and 24.3% ± 0.91, respectively. Based on the 16S rRNA gene sequence, the SHA302 strain showed 93.98% phylogenetic similarity with Bacillus pumilus strain ATCC 7061. The Fourier transform infrared spectroscopy and thin-layer chromatography results proved that the biosurfactants produced by isolates SHA302, SH21 and SH72 showed lipopeptide, glycolipoprotein and glycoprotein natures, respectively. The performance of the biosurfactant produced by SHA302 isolate indicated that it could be used as a good candidate for releasing TPH from saline-sodic soils with old contamination and facilitating the degradation of hydrocarbons.