Exploring marine and psychrophilic bacteria for biosurfactant production and oil spill mitigation

Crude oil spills pose a serious menace to aquatic habitats. While bioremediation offers a sustainable solution, challenges like slow degradation and heavy oil loads persist. This study investigates the potential of extremophilic bacteria from underexplored marine and cold-active habitats to address these restrictions. Four potential Bacillus strains, two from seawater ( Bacillus vallismortis VSL-2 and B. subtilis IS-5), and two from a cold-active site ( B. subtilis EXSP-1 and B. subtilis PPSL-2), were identified and designated as IS-1, IS-5, EX-1, and EX-2, respectively. The isolated strains produced biosurfactant with notable concentrations of 5.5 ± 0.7 (IS-1), 7.6 ± 0.2 (IS-5), 3.2 ± 0.2 (EX-1), and 4.5 ± 0.4 g L −1 (EX-2). The produced biosurfactant (lipopeptides) by IS-5 could significantly reduce the surface tension (mN/m) of water from 72 to as low as 29. The biosurfactant showed effective antimicrobial properties against a broad spectrum of pathogenic bacterial groups and was stable across a wide range of physical conditions. The novel strains demonstrated an efficient biosurfactant-mediated oil degradation efficiency under simulated marine conditions. Strain IS-5 exhibited a remarkable crude oil (1 g L −1 ) degradation efficiency of 90 % in the presence of externally supplemented biosurfactant. The GC–MS study revealed a significant degradation of aliphatic hydrocarbons by 63 %, 69 %, 48 %, and 59 %, and for aromatic hydrocarbons by 60 %, 61 %, 21 %, and 71 % via the isolates IS-1, IS-5, EX-1, and EX-2, respectively. Therefore, these newly isolated strains can potentially be explored for scale-up biosurfactant production and utilized in oil spill cleanups, pharmaceuticals, and other industrial applications. • Four biosurfactant (BS) producing Bacillus strains isolated from marine/cold sites. • IS-5 achieved 90 % oil degradation at 0.5 CMC BS in simulated seawater conditions. • Isolates effectively degraded aliphatic and aromatic hydrocarbons as shown by GC–MS. • Biosurfactants markedly reduced surface tension and exhibited antibacterial activity. • Lipopeptide biosurfactant showed stability under diverse environmental conditions.