eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2025-12-30 22 4 1564 1579 10.13005/bbra/3460 57163 article Boski Thakkar 1 Nisha Daxini 1 Department of Biotechnology, Institute of Science and Technology for Advanced Studies and Research – ISTAR, The Charutar Vidya Mandal (CVM) University, Vallabh Vidyanagar, Gujarat, India Biosurfactants from halophilic bacteria represent a promising sustainable alternative to synthetic surfactants, particularly when produced from waste substrates. This study investigated biosurfactant production by halophilic bacteria isolated from coastal marine waters using waste vegetable oil as a carbon source. Six halophilic bacterial isolates were obtained from seawater samples collected from Dhuvaran, Dandi, Dwarka, and Daman coastal regions of India. Among these, isolates Dh4 and Dm2 exhibited superior biosurfactant production, achieving yields of 2.3 g/100 mL and 2.1 g/100 mL, respectively, in a mineral salt medium supplemented with 2% waste vegetable oil. The produced biosurfactants demonstrated significant surface-active properties, reducing surface tension and showing oil displacement zones of 7.5 cm and 7.8 cm for Dh4 and Dm2, respectively. Emulsification indices (E24) reached 42% and 47%, indicating strong emulsifying capacity. Preliminary biochemical characterisation revealed the presence of glycolipid biosurfactants, as confirmed by saponification and Fehling's tests. FTIR spectroscopy identified characteristic functional groups including C-H stretching (2923.57, 2853.24 cm⁻¹), C=O stretching (1714.39 cm⁻¹), and C=C stretching (1636.88 cm⁻¹), consistent with glycolipid structures. The biosurfactants exhibited potent antiadhesive activity against pathogenic bacteria, inhibiting biofilm formation by Bacillus subtilis (75.33%), Escherichia coli (39.3%), Pseudomonas aeruginosa (28.26%), and Salmonella paratyphi (13.5%) at a concentration of 5 mg/mL.  Antimicrobial activity against these pathogens was also demonstrated. These findings highlight the potential of halophilic bacteria for sustainable biosurfactant production from waste oily substrates, offering promising applications in biomedical and environmental fields, particularly for combating biofilm-associated infections. https://www.biotech-asia.org/vol22no4/sustainable-production-of-glycolipid-biosurfactants-by-halophilic-bacteria-utilizing-waste-vegetable-oil-insights-into-antimicrobial-and-antiadhesive-properties/ Antiadhesive Activity; Biofilm Inhibition; Biosurfactant;  Glycolipid; Halophilic Bacteria; Sustainable Production; Waste Vegetable Oil