Rhamnolipids_GC-MS Analysis of the Fatty Acids

Oil exploration and production are increasingly shifting to deeper offshore environments, where accidental hydrocarbon releases pose a significant threat. Subsea oil spills like the Deepwater Horizon demonstrated the large-scale application of chemical dispersants, including subsea injection, as a primary response measure. However, uncertainties remain regarding dispersants’ performance and environmental implications under deep-sea conditions. This has prompted interest in alternative biologically derived surface-active agents that may combine dispersive action with enhanced biodegradation potential and reduced environmental impact. Exploring the biotechnological potential of indigenous deep-sea marine microorganisms in particular, is crucial for identifying unique biosurfactants as an alternative to chemical dispersants. In this context, we investigated the capacity of a deep-sea microbial consortium from 1,000 m depth in the Eastern Mediterranean, an emerging area of deep-sea hydrocarbon exploration and exploitation, to produce biosurfactants under simulated <i>in situ</i> conditions (100 bar, 14 °C), with crude oil (0.5% v/v) as the sole carbon source and nutrient amendments. Biosurfactant activity was detected during incubation, and glycolipid-type biosurfactants were isolated from the culture medium. Following purification by silica gel chromatography, a total rhamnolipid yield was 41.3 mg L⁻¹ (~10 mg g⁻¹ oil). Rhamnolipids were separated into mono- and di-rhamnolipid fractions and characterized for their functional groups (FTIR) and fatty acyl composition (GC–MS). FTIR confirmed the glycolipid nature of the extracts, while GC–MS revealed β-hydroxy fatty acids ranging from C6:0 to C18:0, demonstrating that deep-sea consortia can synthesize structurally diverse rhamnolipids under <i>in situ</i> conditions and supporting their operational relevance for subsea spill response. Our findings highlight biosurfactants as viable, environmentally aligned candidates for integration into future oil spill response strategies.