Algicidal activity of renewable and ecofriendly sophorolipid biosurfactants

Authors: Msanne, Joseph; Ashby, Richard; Mullen, Charles; Uknalis, Joseph

Submitted to: Journal of Surfactants and Detergents
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2026
Publication Date: 5/5/2026
Citation: Msanne, J.N., Ashby, R.D., Mullen, C.A., Uknalis, J. 2026. Algicidal activity of renewable and ecofriendly sophorolipid biosurfactants. Journal of Surfactants and Detergents. https://doi.org/10.1002/jsde.70031.
DOI: https://doi.org/10.1002/jsde.70031

Interpretive Summary: In aquatic systems, algae treatment with chemical compounds may result in major ecological impacts due to residual chemical contamination and ecotoxicity. Furthermore, many disinfectants regularly used in swimming pools may cause skin irritation and produce unpleasing odors. In this study, the novel algicidal effects of renewable and ecofriendly sophorolipid (SL) glycolipids, produced by the yeast Starmerella bombicola, have been investigated against representative algal isolates considered as most common swimming pool algae. Results confirmed algal growth inhibition in media containing SL biosurfactants even at low concentrations despite the variability in species responses; moreover, certain forms of SL from S. bombicola showed strong cell damage activity toward all isolates at higher concentrations. This original laboratory-scale research demonstrates the immense potential of biodegradable SLs as economical and effective cell-disrupting, algicidal compounds with high efficacy and reduced environmental impacts. This research was also essential for the identification of effective treatment concentrations and the analyses of impacts at the cellular level. Results from this research may benefit algae bloom prevention and provide solid basis for commercial applications.

Technical Abstract: The algicidal effects of renewable and ecofriendly sophorolipid (SL) glycolipids produced by the yeast Starmerella bombicola were investigated under controlled laboratory conditions, against species of algae commonly encountered and identified in swimming pools. Algae species tested in the present study included the green algae Chlamydomonas reinhardtii CC-125 and Chlorella sorokiniana UTEX 1230, the yellow green alga Eustigmatos vischeri UTEX 310 (Pleurochloris commutata), and the cyanobacterium Phormidium autumnale UTEX B 1580. A range of SL concentrations was tested in 10-day laboratory experiments to assess algicidal performance, and to monitor cell growth and evaluate effectiveness in the control of all tested algae. Results indicated that growth was strongly inhibited at the optimal sophorolipid concentration of 0.025 mg/mL, and algal cell densities significantly declined within 1 to 4 days after treatment (DAT) as compared to untreated controls. At this concentration, algae were irreversibly damaged with no recovery occurring throughout the experimental period. No significant changes in biomass were noticed at lower SL concentrations. Responses were also measured at 2 DAT in terms of total chlorophyll content. At the minimum SL concentration of 0.025 mg/mL, cultures exhibited increased bleaching with chlorophyll declining over 80% for all tested species. Microscopy analyses also confirmed the sensitivity to sophorolipid treatments. Although responses were species specific, some algae including C. reinhardtii and E. vischeri were more easily lysed at high concentrations (1 mg/mL). These preliminary results highlight the potential of sophorolipids as alternative to chemical treatment options, and a novel and effective method in mitigating algal species commonly found in swimming pools.