Leveraging the Green Petroleum Hydrocarbon Remediation Potential of a Biosurfactant Producing Indigenous Oleophilic Bacterium Isolated from Hydrocarbon Soiled Environment

The present investigation focused on the physicochemical characterization and bioprospecting of an indigenous oleophilic bacterium (OB) and its biosurfactant (BS) for bioremediation. Within 14 days of culture at 30°C with 2% (v/v) n-hexadecane, the OB could reduce the surface tension of the culture medium by up to 34.4 mNm-1. Standard screening tests verified that the isolated OB produced BS and identified it as Pseudomonas aeruginosa. BS production was 434.7 mg.L-1, with a CMC of 195.6 mg.L-1, and was purified and characterized using standard chromatographic and spectroscopic techniques. FTIR analysis confirmed the glycolipid nature of BS. TLC of the partially purified BS revealed two homologues of rhamnolipid (RL), which were subsequently confirmed by NMR. Seven distinct RL congeners were identified using LC-MS, of which di-RLs constituted a notably large proportion. The surface and emulsification activities of BS demonstrated significant stability against various pH levels, temperatures, salinities, and metal ions. Furthermore, OB was able to utilize crude oil within 60 days, as confirmed by GC-MS. In the soil washing experiment, BS separated ≥80% of the crude oil from the contaminated sand at the CMC. The results suggest that the RLs and their producer isolated from automobile workshops in Mokokchung are not only the first report from Nagaland, India, but are also promising for various applications in the bioremediation of extreme and complex environments, including addressing regional environmental issues in Nagaland.