Production of lipase by a strain of the non-conventional yeast Yarrowia lipolytica and isolation of crude enzyme

Fermentation experiments were performed at laboratory level, in shake flasks and batch culture system. Lipase production by a wild strain of Yarrowia lipolytica was investigated in cultivation media containing: glucose as carbon and energy source, peptone bacto and yeast extract as the most suitable nitrogen sources, mineral salts (MgSO4, KH2PO4) and olive oil (0,05 - 2%). The study was focused on the dependence of lipase biosynthesis on aeration and olive oil concentration. Four levels of aeration and five variants of the above mentioned cultivation medium were compared with respect to lipase production and the optimum values of these parameters were established. Precipitation with ethanol was used to isolate crude lipase from the fermentation liquid, after removing the biomass by centrifugation. Aiming to recover the native enzyme as much as possible, our experiments pointed out the optimal conditions for lipase precipitation with ethanol, taking into account the influence of the following parameters: enzymatic solution/ethanol ratio, solvent-enzyme contact duration, precipitation temperature, Ca2+ concentration as stabilizer-activator.