Encapsulation in a sol–gel matrix of lipase from Aspergillus niger obtained by bioconversion of a novel agricultural residue

Abstract

Lipase from Aspergillus niger was obtained from the solid-state fermentation of a novel agroindustrial residue, pumpkin seed flour. The partially purified enzyme was encapsulated in a sol-gel matrix, resulting in an immobilization yield of 71.4 %. The optimum pH levels of the free and encapsulated enzymes were 4.0 and 3.0, respectively. The encapsulated enzyme showed greater thermal stability at temperatures of 45 and 60 °C than the free enzyme. The positive influence of the encapsulation process was observed on the thermal stability of the enzyme, since a longer half-life t 1/2 and lower deactivation constant were obtained with the encapsulated lipase when compared with the free lipase. Kinetic parameters were found to follow the Michaelis-Menten equation. The K m values indicated that the encapsulation process reduced enzyme-substrate affinity and the V max was about 31.3 % lower than that obtained with the free lipase. The operational stability was investigated, showing 50 % relative activity up to six cycles of reuse at pH 3.0 at 37 °C. Nevertheless, the production of lipase from agroindustrial residue associated with an efficient immobilization method, which promotes good catalytic properties of the enzyme, makes the process economically viable for future industrial applications.

<b>Lipase from <i>Aspergillus niger</i> obtained from mangaba residue fermentation: biochemical characterization of free and immobilized enzymes on a sol-gel matrix

“…The enzyme was obtained by state solid fermentation of mangaba seeds as described by Zubiolo et al (2014). The fermentations were conducted in Petri dishes containing 10 g of residue (30% moisture content) and a spore suspension of Aspergillus niger (10 6 spores g -1 ) at a temperature of 30°C.…”

“…The enzymatic activity of the free and immobilized lipase was determined by the hydrolysis method using olive oil according to the procedure described by Zubiolo et al (2014). The substrate was prepared using 50 mL of olive oil and 50 mL of gum Arabic solution (7% w v -1 ).…”

“…These results are in accordance with the literature, since lipases from Aspergillus sp. have been shown to have an optimum pH between 2.5 and 6.0 and greater stability between pH 7.0 and 11.0 (Contesini, Lopes, Macedo, Nascimento, & Carvalho, 2010;Mahadik, Puntambekar, Bastawde, Khire, & Gokhale, 2002;Mhetras, Bastawde, & Gokhale, 2009;Zubiolo et al, 2014).…”

“…In such cases, exogenous supplementation becomes necessary (Salihu et al, 2012;Pandey, Selvakumar, Soccol, & Nigam, 1999). Residues such as wheat bran, rice bran, soybean bran, barley bran, soy oil cake, olive oil cake, gingelly oil cake, babassu oil cake, coconut oil cake, sugarcane bagasse and pumpkin seeds have been reported to be effective for lipase production (Edwinoliver et al, 2010;Salihu et al, 2012;Zubiolo et al, 2014).…”

Immobilized Aspergillus niger Lipase with SiO2 Nanoparticles in Sol-Gel Materials

“…Ahmed et al immobilized A. niger lipase with magnetic barium ferrite nanoparticles and increased the enzyme activity [28]. However, the activity was greatly decreased when encapsulating the lipase in a sol-gel matrix [29]. In this work, we designed a different protocol for the sol-gel synthesis which may have been the key factor that contributed to the higher activity recovery (as shown in Table 4).…”