Low toxicity and high surface activity of sophorolipids from Starmerella bombicola in aquatic species: A preliminary study

摘要

Aim: This study was carried out to evaluate aquatic toxicity and surface activity of sophorolipids extracted from yeast Starmerella bombicola.Methodology: The half maximal effective concentration (EC50) values of sophorolipids were determined in three aquatic species, and the surface activity of sophorolipids in aqueous solutions was examined at EC50 concentration.Results: The EC50 of sophorolipid surfactant 473 mg l(-1) was found in alga Pseudokirchneriella subcapitata, a median lethal concentration (LC50) of 64.8 mg l(-1) in fish Oryzias latipes, whereas a high EC50 of 48.2 mg l(-1) was noted in crustacean Daphnia magna, respectively. Sophorolipids effectively reduced the aquatic surface tension to 39 mN m(-1) in O. latipes and to 41 mN m(-1) in D. magna.Interpretation: These results show that sophorolipids from S. bombicola are a promising biosurfactant with an ideal balance of low aquatic toxicity and high surface activity.