Yarrowia lipolytica uses olive tree prunings hydrolysates for microbial lipids as biodiesel feedstock

• A maximum cellulose content of 42 % was achieved at 200 °C for 15 min. • OTPH after enzymatic hydrolysis at 20 % solid loading had 125 g/L of glucose. • Y. lipolytica produced 27 g/L of lipids and 25 g/L of citric acid in undiluted OTPH. • Lipid concentration achieved is the highest reported for yeasts in OTPH. • Estimated properties of biodiesel meet the quality international standards. Efficiently valorizing olive tree prunings (OTP) for microbial lipids represents an excellent strategy to achieve resource circularity, accompanied by economic and environmental benefits. Since the production of lipids from OTP hydrolysate (OTPH) by yeasts remains underexplored, this study investigated the potential of Y. lipolytica to produce lipid-rich biomass in bioreactor batch cultures. OTP was fractionated by combining hydrothermal pretreatment with enzymatic hydrolysis, obtaining a glucose-rich (125 g/L) OTPH. Undiluted OTPH proved to be a suitable substrate, leading to the production of 78 g/L biomass, enriched with 26.8 g/L lipids, and 25 g/L citric acid. The lipids concentration achieved is the highest reported for yeasts in lignocellulosic biomass hydrolysates. Intracellular lipids were highly unsaturated, mainly composed of oleic acid. The estimated properties of biodiesel that would be obtained using Y. lipolytica lipids are per international standards. This study is a starting point for a potential biorefinery approach using OTP as a raw material for biodiesel production.