Application of a Biosurfactant from Starmerella bombicola ATCC 22214 for the Removal of Hydrophobic Compounds from Contaminated Surfaces

Abstract

Petroleum-derived hydrophobic pollutants represent a persistent environmental concern, highlighting the need for sustainable and efficient remediation technologies. In this study, a biosurfactant produced by the yeast Starmerella bombicola ATCC 22214 using glucose and glycerol as carbon sources was characterized and evaluated for the removal of hydrophobic contaminants from different surfaces. Ionic-charge analysis indicated an anionic biosurfactant, while FTIR and 1H/13C NMR analyses revealed spectral characteristics consistent with sophorolipid-type glycolipids, including a polar carbohydrate moiety associated with sophorose, ester and carbonyl functionalities, and long fatty-acid-derived aliphatic chains. The biosurfactant maintained its surface activity during 120 days of storage under different preservation conditions, with surface tension values remaining at approximately 32 ± 2 mN/m. In the Allium cepa assay, no visible cytogenetic alterations were observed at concentrations of 0.2, 0.4, and 0.8 g/L. The biosurfactant showed maximum apparent removal values, calculated relative to the nominal oil mass applied, of up to 86.61% for used engine oil on porous rocks and 77.90% for OCB1 heavy oil on metal surfaces, while 84.00% removal was obtained for burnt engine oil from cotton fabric. These findings indicate that the biosurfactant produced by S. bombicola ATCC 22214 presents structural features consistent with a sophorolipid-type glycolipid, prolonged surface activity, no visible cytogenetic alterations under the conditions of the preliminary qualitative screening, and promising performance for the removal of petroleum-derived hydrophobic contaminants from different surfaces.