Exploring the potential of novel Bacillus sp. G6: Isolation, characterization, and optimization of biosurfactant production from oil-contaminated soil

Abstract

Biosurfactants (BSs) are highly biodegradable, environmentally benign, and multifunctional substances having diverse industrial uses, including environment bioremediation. Because of its remarkable emulsifying properties, as well as its use in both the environment and medicine, surfactin, is considered one of the most potent BSs and belongs to the lipopeptides family. The present study was performed to isolate the potential bacteria from oil-contaminated soils. Selected bacteria were checked for biosurfactant (BS) synthesis and their characterization. Out of 32 bacteria, the most promising isolate G6 was taken for a detailed study. Based on polyphasic taxonomy it was found to belong to the novelBacillussp.Nutrient screening for higher BS synthesis usingthe Plackett-Burman design(PBD) showed thatFeSO4, NaCl andwaste engineoil have a significant influence on BS production. Further optimization utilizingBox-Behnken design(BBD) revealed that the optimized condition for higher BS synthesis wasFeSO4(2.0 %), NaCl (2.0 %), and waste engine oil (2.2 %). The highest BS yield of 3.79 ± 0.265 g/L was attained with a cell biomass of 1.51 ± 0.234 g/L with 1.92 fold increase in the yield. Based on thin-layer chromatogram (TLC),Fourier transform infrared spectroscopy(FTIR), andGas Chromatogram-Mass Spectrometry(GC–MS) studies it was observed that the probable BS was a surfactin-like molecule that is stable at a wide range of temperature (up to 100° C), pH (5–9), and salinity (3–6 %).