Olive and sunflower cakes as suitable substrates for lipase production by Yarrowia spp.: From flasks to bioreactor

Abstract

Solid state fermentation is a biotechnological process that allows the utilization of agro-industrial by-products as solid substrates for the growth of microorganisms, including filamentous fungi and yeasts, with the simultaneous production of added value compounds, like enzymes. Oil cakes, such as olive and sunflower cakes, are generated during vegetable oil extraction and have received great interest as solid substrates in SSF processes. In the present work, a 50% (w/w) mixture of olive and sunflower cakes was used as substrate in SSF for lipase production by several strains of Y. lipolytica and Y. divulgata. The strain of Y. lipolytica W29 was the best lipase producer under small scale SSF and studies were conducted to address important factors in scaling-up the process. Different bioreactors were used and the effect of aeration and agitation on lipase production was studied. Higher lipase activity was obtained in tray bioreactors, reaching 85 U/g (dry mass of substrates) after 48 h of SSF, while the operation in a horizontal drum bioreactor favored yeast growth, resulting in the highest yeast biomass production and a delay in lipase maximum activity. The scale-up of SSF for lipase production by Y. lipolytica has been successfully performed, showing that SSF is an interesting and eco-friendly bioprocessing strategy for the valorization of by-products from vegetable oil industries.