The world market for biosurfactants has grown gradually. However, the lack of competitiveness with chemical surfactants due to high cost of production remains a concern. Considering the need to reduce the costs of production, the aim of this work was to study the production and structural characterization of a biosurfactant produced by a strain of yeast Candida glabrata UCP 1556. The low-cost medium containing agro-industrial wastes whey 40% (v/v) and 20% (v/v) corn steep liquor were used as substrates in submerged fermentation. Biosurfactant production was detected by surface tension, oil displacement test and Critical Micelle Concentration (CMC). The structural characterization was performed by Fourier transform infrared (FT-IR), gas chromatography-mass spectrometry (GC-MS) and ionic profile. The stability of emulsions and potential in reducing the viscosity also were investigated. The results showed that the biosurfactant reduced the surface tension to 28.8 mN/m with CMC of 2% and showed anionic profile. Additionally, the biosurfactant formed stable emulsions at temperature (0 to 120°C), pH (2 to 12) and NaCl (2 to 12%), reduced the viscosity of soybean oil (21.0 to 18.5 Cp), cotton (39.5 to 26.4 Cp) and canola (34.8 to 29.3 Cp) and has oil dispersing capacity of 81.54%. The chemical structure of biosurfactant exhibited absorption in peaks characteristic of lipids represented at 1393 cm-1 (chain of fatty acids) and the presence of peptides was confirmed by the presence of the peak at 1662 cm-1. The biosurfactant is constituted by 58% of lipids and 36% of protein. The fatty acids of the hydrophobic portion of biosurfactant were capric acid (4.1%), palmitoleic acid (33.6%), steric acid (28.4%), oleic acid (22.6%) and linoleic acid (5.7%). The results demonstrated that C. glabrata can produce an anionic lipopeptide biosurfactant in low-cost medium with promising conditions for the production in large scale.
Key words: Candida glabrata, lipopeptide, agro-industrial wastes, physicalchemical characterization.
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