ABSTRACT
Aims: Fermentation and recovery are the major operating cost in biosurfactant production. Thus, the aim of this research was to synthesize biosurfactant from agricultural residues using suitable fermentation and recovery techniques in order to reduce the cost of production. Methodology and results: Biosurfactant-producing yeast strains isolated from refined oil-contaminated soil samples using yeast extract-diesel agar (YEDA) were subjected to physicochemical screening such as drop collapse test, microplate analysis, oil spreading technique, emulsification index and thermostability. Based on the preliminary screening result, Candida lusitaniae P1, C. parapsilosis P51, C. parapsilosis D3 and C. lusitaniae E1 were selected for biosurfactant production using agricultural residue such as rice bran, wheat bran and coconut shell as substrate and crude supernatant was analyzed by gas chromatography mass spectrometry. Candida lusitaniae P1 strain produced 98.96 g/L of biosurfactant from coconut shell but when subjected to mutagenesis the yield decreased to 52.24 g/L. Conclusion, significance, and impact of study: The physicochemical properties of biosurfactant produced using various carbon sources showed that coconut-shell is the best residue thus, variation in composition and concentration of biosurfactant obtained implies that the quality and quantity of biosurfactant produced depends on the carbon source and the genetic composition of the yeast isolate.