Unraveling the Potential of Yarrowia lipolytica to Utilize Waste Motor Oil as a Carbon Source.

Abstract

This study evaluated the potential of Y. lipolytica (CBS 2075 and DSM 8218) to grow in waste motor oil (WMO) and produce valuable compounds, laying the foundation for a sustainable approach to WMO management. Firstly, yeast strains were screened for their growth on WMO (2-10 g·L^-1) in microplate cultures. Despite limited growth, the CBS 2075 strain exhibited comparable growth to control conditions (without WMO), while DSM 8218 growth increased 2- and 3-fold at 5 g·L^-1 and 10 g·L^-1 WMO, respectively. The batch cultures in the bioreactor confirmed the best performance of DSM 8218. A two-stage fed-batch strategy-growth phase in aliphatic hydrocarbons, followed by the addition of WMO (one pulse of 5 g·L^-1 or five pulses of 1 g·L^-1 WMO), significantly increased biomass production and WMO assimilation by both strains. In experiments with five pulses, CBS 2075 and DSM 8218 strains reached high proteolytic activities (593-628 U·L^-1) and accumulated high quantities of intracellular lipids (1.3-1.7 g·L^-1). Yeast lipids, mainly composed of oleic and linoleic acids with an unsaturated/saturated fraction > 59%, meet the EU biodiesel standard EN 14214, making them suitable for biodiesel production.