Waste cooking oils as feedstock for lipase and lipid-rich biomass production

Abstract

Approximately 1 million tons of waste cooking oils (WCO) are generated in European Union per year. Oftentimes, these oily wastes are discharged through public sewerage systems, increasing the water treatment costs in wastewater treatment plants. The oleaginous yeast Yarrowia lipolytica W29 was used to simultaneously degrade WCO and to produce lipase (market demand is increasing due to its application in the field of bioenergy). A statistical experimental design based on Taguchi method was employed to assess the effect of initial medium pH, WCO and arabic gum concentration on lipase production. Initial medium pH was found to be the most significant parameter and the interaction between WCO and arabic gum concentration had the highest influence for lipase production. Additionally, the effect of oxygen mass transfer was studied in batch cultures in a stirred tank bioreactor and the maximum lipase activity (12000 U·L1) was obtained at kLa of 16 h1. Simultaneously with lipase production, also lipidrich biomass (48% of lipids mass per dry cellular mass), enriched in unsaturated fatty acids (oleic and linoleic acids) was obtained.