Study on effective conditions for sophorolipid extraction from Candida bombicola fermentation broth and testing its biological activity

Abstract

Sophorolipid (SL) is a potential biosurfactant due to its biodegradability, low toxicity and eco-friendly criteria, produced by Candida bombicola, a non-pathogenic yeast. To extract SL from fermentation broth efficiently, a study on effective conditions for SL extraction from Candida bombicola fermentation broth was conducted. The result showed that the optimal conditions for extracting SL from the fermentation broth included ethyl acetate:fermentation broth 1:1 (v:v) and petroleum ether:methanol:fermentation broth 1:1:1 (v:v:v) with the SL extraction efficiency and fat removal capacity from 90% and 97%, respectively, while the total SL and soybean oil in the fermentation broth did not exceed 20%. The recovery performance of such solvents as ethyl acetate (EtAc), methanol (MeOH), petroleum ether (PE) in SL extraction process were from 91-92%, 78-83%, 32- 43%, respectively (with the contents of SL and soybean oil from 2 to 20%). The obtained SL at the concentration of 100 mg/ml showed a high antimicrobial activity, the highest resistance to Bacillus spizizenii (13.67±0.58 mm), then relatively high resistance to Staphylococcus aureus (12.67±1.15 mm), Pseudomonas aeruginosa (11.33±0.58 mm) and Escherichia coli (9.67±0.58 mm). The antioxidant capacity of SL was performed with an IC50 of 6.024 mg/ml. These results indicate that SL is one of the most promising microbial biosurfactant with highly potential applications in cosmetics, detergents and other commercial applications related to surfactants.