Enhanced bioremediation of hydraulic fracturing flowback and produced water using an indigenous biosurfactant-producing bacteria Acinetobacter sp. Y2

[Display omitted] •An indigenous biosurfactant producer Acinetobacter sp. Y2 was isolated from HF-FPW.•Biosurfactant produced by Y2 showed excellent surface activity and stability.•Notable COD and petroleum hydrocarbon removals were achieved by the Y2 inoculation.•The underlying mechanism for the enhanced bioremediation was raised in this study.•A promising in situ strategy for HF-FPW bio-treatment was proposed. In this study, a biosurfactant-producing strain Y2 was isolated from hydraulic fracturing flowback and produced water (HF-FPW) and identified as Acinetobacter sp. The biosurfactant produced by Y2 could reduce surface tension of water from 72.2 mN/m to 30.2 mN/m with a CMC value of 187.5 mg/L and showed strong tolerance against wide ranges of pH (2–12), temperatures (4–100 °C), and salinity (0–100 g/L). Through thin layer chromatography, Fourier transform infrared spectroscopy, and gas chromatography–mass spectrometry analysis, the biosurfactant was characterized as lipopeptide. Inoculation of Acinetobacter sp. Y2 into HF-FPW greatly increased the activity and growth of the microcosm. Meanwhile, it significantly (P