Valorization of Macauba (Acromia aculeata) for Integrated Production of Lipase by Yarrowia lipolytica and Biodiesel Esters

Enzymatic biodiesel production is a potential eco-friendly alternative to the conventional chemical route which requires extensive study to reduce the costs associated with the application of commercial enzymes. Thus, this study aimed to develop a bioprocess using residues from macauba (Acrocomia aculeata) as raw material for lipase production in solid-state fermentation (SSF) by Yarrowia lipolytica. Then, the product obtained was used as a biocatalyst for the conversion (hydrolysis/esterification) of macauba acidic oil to biodiesel esters. Firstly, different SSF parameters (inoculum concentration, initial moisture content, and carbon and nitrogen levels) were investigated in a factorial design approach, using the cake from macauba fruit. Afterwards, moisture and urea concentration were shown to be statistically significant variables for lipase production. Lipase productnivities were 12.6 +/- 0.6 U g(-1) h(-1) (at 24 h) for macauba fruit cake and 11.6 +/- 1 U g(-1) h(-1) (at 20 h) for macauba pulp and peel cake. The solid enzymatic preparation (biocatalyst) showed optimized values at pH 6-7 at 37 degrees C, remaining stable (>70% retention) for 90 days at room temperature. Finally, enzymatic hydrolysis of the acidic oil from macauba reached 96% conversion (72 h) to fatty acids, and esterification of fatty acids reached 72% (biodiesel yield of 67%). The bioprocess described is a promising alternative for an integral and self-sufficient valorization of the macauba products.