Characterization and Stability of Biosurfactant Produced by Xanthomonas campestris Isolated from Tannery Effluent

The structural characterization of biosurfactants produced by Xanthomonas campestris isolated from tannery effluents was performed using Fourier Transform Infrared Spectroscopy (FT-IR) and Gas Chromatography–Mass Spectrometry (GC–MS). FT-IR analysis revealed distinct functional groups consistent with amphiphilic biosurfactants. A broad band at 3339 cm⁻¹ indicated O–H stretching associated with hydroxyl groups, while a strong absorption at 1640 cm⁻¹ corresponded to amide carbonyl groups. Peaks at 1220 cm⁻¹ and 1019 cm⁻¹ confirmed C–O and C–O–C vibrations typical of sugar moieties, whereas low-frequency peaks at 750 cm⁻¹ and 672 cm⁻¹ represented C–H bending of long hydrocarbon chains. These results support the presence of both hydrophilic and hydrophobic domains, consistent with glycolipid-type biosurfactants. GC–MS analysis further confirmed this classification, detecting fatty acid fragments (57.1–257.3 m/z) that constitute the hydrophobic region, alongside a diagnostic sugar fragment at 183.2 m/z indicative of rhamnose. High molecular weight fragments (467.6–593.7 m/z) corresponded to intact or partially fragmented glycolipid conjugates. The combined evidence strongly suggests the biosurfactant is a rhamnolipid-like glycolipid with structural complexity that explains its emulsifying and surface-active properties and the crude biosurfactant from Xanthomonas campestris showed stability at pH 8, 45 °C, and 10% NaCl. These findings highlight the potential of X. campestris from tannery effluents as a promising source of glycolipid biosurfactants for environmental and industrial applications.