Bioproduction and Anticancer Activity of Biosurfactant Produced by the Dematiaceous Fungus Exophiala dermatitidis SK80

A new biosurfactant producer was isolated from palm-oil-contaminated soil and later identified through morphology and DNA sequencing as the yeast-like fungus Exophiala dermatitidis. Biosurfactant production was catalyzed by vegetable oil, supplemented with a basal medium. The culture conditions that provided the biosurfactant with the highest surface activity were found to be 5% palm oil with 0.08% $NH_4NO_3$, at a pH of 5.3, with shaking at 200 rpm, and a temperature of $30^{\circ}C$ for a 14-day period of incubation. The biosurfactant was purified, in accordance with surfactant properties, by solvent fractionation using silica gel column chromatography. The chemical structure of the strongest surface-active compound was elucidated through the use of NMR and mass spectroscopy, and noted to be monoolein, which then went on to demonstrate antiproliferative activity against cervical cancer (HeLa) and leukemia (U937) cell lines in a dose-dependent manner. Interestingly, no cytotoxicity was observed with normal cells even when high concentrations were used. Cell and DNA morphological changes, in both cancer cell lines, were observed to be cell shrinkage, membrane blebbling, and DNA fragmentation.