Abstract
Environmental pollution caused by crude oil contamination poses a major ecological threat, highlighting the need for sustainable bioremediation approaches. Biosurfactants produced by actinobacteria offer promising advantages due to their eco-friendly and multifunctional properties. In this study, soil samples were collected from oil contaminated sites in and around Salem, Tamil Nadu, India. Eight morphologically distinct isolates were screened based on β-hemolysis, oil displacement, emulsification index, and lipase activity. Among them, strain AS1 demonstrated the highest biosurfactant activity. Molecular identification through 16 S rRNA gene sequencing confirmed that AS1 belongs to the genus Streptomyces and submitted to GenBank with an accession number-MT525319. The potent strain exhibited strong crude oil degradation capabilities, achieving 95.9% degradation after 168 h as determined by hydrocarbon utilization tests, DCPIP assay, and gravimetric analysis. The biosurfactant extracted from strain AS1 showed notable antibacterial activity against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli, with low minimum inhibitory concentrations, and demonstrated considerable antioxidant potential with 70.04% DPPH radical scavenging activity at 500 µg/ml. Purification by dialysis yielded a partially purified biosurfactant that was characterized by TLC, FT-IR, and GC-MS analyses. FT-IR spectra revealed the presence of functional groups such as alkanes and carboxylic acids, while GC-MS identified several bioactive compounds, including 1-tetradecanol and phthalic acid derivatives. These findings suggest that Streptomyces sp. AS1 strain is a promising candidate for crude oil bioremediation and the development of biosurfactant based applications in pharmaceutical and environmental industries.