Increasing the production of extracellular biosurfactants from Saccharomyces cerevisiae

Biosurfactants possess surface and interfacial activity, low toxicity, high biodegradability, and stability in wide ranges of pH and temperature, which makes them competitive against the existing synthetic surfactants. However, economic aspects are still a barrier to the application in industrial scale. In order to optimize the production processes, the aim was to evaluate the production of extracellular biosurfactants from Saccharomyces cerevisiae using cellular stress techniques. The yeast was tested for six different stress conditions: ethanol, hydrogen peroxide, pH, temperature, ultraviolet radiation, and freezing/thawing. After exposure to different levels of stress, the biosurfactant production was verified from the formation of stable emulsions and reduction of the surface tension of the culture medium. Results showed a higher resistance of the yeast to stressors, being the highest yields found in ultraviolet radiation and hydrogen peroxide, reaching 1.39 and 1.16 UE d⁻¹, respectively. Highest surface tension reduction (11 mN m⁻¹ d⁻¹ in 1 d of fermentation) was obtained for the strain stressed by ethanol at 50%. A positive influence was observed in the use of stress techniques over productivity, indicating the production of extracellular biosurfactants, which could low the costs with the downstream process of these bioproducts.