Evaluation of ecotoxicological effects of sophorolipids on duckweed, Spirodela polyrrhiza

This study evaluated the ecotoxicological effects of sophorolipids (SLs), biosurfactants with potential environmental applications, on the aquatic plant Spirodela polyrhiza (duckweed). Key growth indicators, including biomass, foliose thalli, and leaf area, were examined under varying SL concentrations. Results indicated that low to moderate SL concentrations (below 100 mg/L) had minimal adverse effects on duckweed growth, whereas higher concentrations (200–300 mg/L) significantly inhibited growth and triggered stress responses. Morphological and physiological assessments revealed that elevated SL concentrations caused substantial frond wilting, root hair damage, and reductions in photosynthetic pigments. Antioxidant responses, such as glutathione (GSH), malondialdehyde (MDA), and catalase (CAT) enzyme activities, increased adaptively at low to moderate SL concentrations but declined at higher levels, indicating severe oxidative stress. Despite these adverse effects, S. polyrhiza exhibited a remarkable ability to degrade SLs even at high concentrations, demonstrating the exceptional biodegradability of SLs. Overall, the findings emphasize the relative safety of SLs at low to moderate concentrations in aquatic environments, underscoring their potential as environmentally friendly surfactants when used responsibly.