Emulsifier production by steroid transforming filamentous fungus Curvularia lunata. Growth and product characterization.

Curvularia lunata IM 2901, the filamentous fungus used for hydrocortisone manufacture, was found to be able to produce an extracellular emulsifying agent on water-soluble compounds with a yield of 2.6 g l(-1). Cell-free culture broth containing the examined agent caused the formation of stable emulsions with hydrophobic compounds of natural and xenobiotic origin. Vegetable and mineral oils were the best substrates for emulsification. Kinetics of surfactant biosynthesis was classified as a mixed growth-associated and non-growth-associated type. The crude emulsifier was isolated from culture fluid by acetone precipitation. Preliminary chemical characterization showed that the studied bioemulsifier contained 34.0% C, 5.7% H, 1.8% N, 0.15% S and was a complex of protein (25%) and polysaccharide (48%). Sugar component was identified as a polymer of D-glucose.