Sustainable production of bio-based surfactants from renewable resources using oleaginous yeasts

Single-cell oils (SCO) are intracellular storage lipids, produced in some un-convectional yeast strains and mainly composed of triacylglycerols (TAGs), that can be converted into industrially useful compounds such as bio-surfactants (sugar ester fatty acids, SFAEs)[1]. Whey permeate, a by-product of milk industry, was used as starting material for yeast growth, thus reducing the environmental burden associated to diary by-products disposal and promoting a circular economy strategy, which turns the waste into new resourceful products [2]. Cutaneotrichosporon oleaginosus was selected as the best strain for both biomass and lipid production in whey permeate medium. The process was scaled-up in bioreactor and optimized comparing different nitrogen sources and medium additives, reaching high lipid content (45-61% corresponding to 30-40 g/L). Then different methods of triglyceride extraction were evaluated starting from lyophilized oily yeasts. The most promising method required a pre-treatment with hot-cold cycles, followed by ultrasound-assisted extraction in organic solvents. The obtained lipid mixture was analysed and then subjected to enzymatic hydrolysis in order to obtain free fatty acids to allow the esterification of a modified sugar. At the end of the project, a fully biobased process will be developed, employing yeasts as fatty acids producers starting from surplus dairy waste and optimizing the chemoenzymatic synthesis of sugarbased biosurfactants. This work was financially supported by Cariplo Foundation (Italy) (call: “Circular Economy for a sustainable future 2020”, project BioSurf, ID 2020-1094). [1] N.S. Neta, J.A. Teixeira, L.R. Rodrigues, Sugar ester surfactants: enzymatic synthesis and applications in food industry, Crit. Rev. Food Sc. Nutr., 2015, 55 (5), 595-610. [2] A.R. Prazeres, F. Carvalho, J. Rivas, Cheese whey management: A review, J. Environ. Manag., 2012, 110, 48–68.