Turning cacay butter and wheat bran into substrate for lipase production by Aspergillus terreus NRRL-255

Abstract

Cacay oil and butter were evaluated as enzymatic inducers for lipase production from Aspergillus terreus NRRL-255 by solid-state fermentation (SSF). Initially, physicochemical characteristics of agro-industrial wastes were evaluated in order to identify a potential solid substrate for lipase production. Higher water absorption index (3.65 g H2O/g substrate), adequate mineral content, great carbon source, and nitrogen concentration were factors that influenced the choice of wheat bran as a solid substrate. Cacay butter presented the highest lipolytic activity (308.14 U g−1) in the screening of lipid inducer. Then, the effects of lipid inducer concentration (cacay butter), temperature, pH, moisture, and fermentation time were evaluated on process performance using multivariate statistical methodology. Under optimal conditions, the highest lipase activity observed was 2,867.18 U g−1. Regarding the lipase characterization, maximum relative activity was obtained at pH 7.0 and at 35 °C. An inhibitory effect was observed for Ca2+, Mn2+, Zn2+, Fe2+, and Cu2+ ions. Lipase activity was increased with the reduction of sodium dodecyl sulfate (SDS) concentration and the increase of Triton X-100. Therefore, the use of wheat bran as a solid substrate combined with cacay butter demonstrated a substantial lipase production, indicating its biotechnological industrial potential.