Valorization of Macauba (Acromia aculeata) for Integrated Production of Lipase by Yarrowia lipolytica and Biodiesel Esters
Filipe Smith Buarque, Marcelle Alves Farias, Júlio Cesar Soares Sales, Adriano Carniel, Bernardo Dias Ribeiro, Verônica Regina de Oliveira Lopes, Aline Machado de Castro, Maria Alice Zarur Coelho
Abstract
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 °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.