Investigation of fermentation conditions for Candida bombicola ACTT22214 from molasses and soybean oil for sophorolipid production

Abstract

Sophorolipid (SL) is a biosurfactant belonging to the glycolipids group and was produced by harmless Candida bombicola ACTT22214 and has been widely used in many fields in our life. In order to search for appropriate condition for C. bombicola fermentation producing SL with high efficiency, this study focused on the investigation of the soy oil concentration, molasses concentration, fermentation time, pH and temperature. SL products were tested for antimicrobial activity, antioxidant, emulsifier, foaming ability. The highest content of SL was 43.27 ± 0.30 g/L under conditions of: soybean oil content 5%, molasses content 150 g/L, fermentation time 7 days, pH = 5, 28oC fermentation temperature. The antibacterial activity of SL was good: the highest resistance to Candida albicans (16.33 ± 1.15 mm), good resistance to Bacillus spizizenii (13.67 ± 0.58 mm), resistance to Staphylococcus aureus (12.67 ± 1.15 mm), relatively weak resistance to Pseudomonas aeruginosa (11.33 ± 0.58 mm) and Escherichia coli (9.67 ± 0.58 mm). The antioxidant capacity of SL was quite high with an IC50 value of 6.024 mg/mL. The emulsifying capacity of SL was equivalent to the emulsification of the tween 20 at a concentration of 5 - 10 mg/mL. SL had the ability to foam evenly from concentrations of 5 to 20 mg/mL but not higher than the corresponding concentrations of tween 20, SL was smooth, even, stable longer than tween 20