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Enzymes are extensively used in biotechnological processes in several areas of industry. They are sustainable and safe, and their specificity is another characteristic that improves the performance in the process. Among enzymes, lipase is relevant due to the ability to play different roles in the industry and the possibility of collecting them from microbial sources that are found in industrial residues. This can reduce the costs of enzyme production. In relation to that, lipase immobilization is an interesting process that allows the enzymes to be reused and improves enzyme robustness. Among them, the cross-linked enzyme aggregates (CLEAs) methodology is attractive due to its simplicity, low cost (given the absence of support), and greater interaction with the substrate. Thus, in this review, we discussed the potential of lipase. We reviewed the traditional and new sources of obtaining lipases, along with the ways of improving production, activity, and application in the industry.

This study mainly aims to find the optimal conditions for immobilizing a non-commercial β-glucosidase from Aspergillus niger via cross-linked enzyme aggregates (CLEAs) by investigating the effect of cross-linking agent (glutaraldehyde) concentration and soy protein isolate/enzyme ratio (or spacer/enzyme ratio) on the catalytic performance of β-glucosidase through the central composite rotatable design (CCRD). The influence of certain parameters such as pH and temperature on the hydrolytic activity of the resulting heterogeneous biocatalyst was assessed and compared with those of a soluble enzyme. The catalytic performance of both the soluble and immobilized enzyme was assessed by hydrolyzing ρ-nitrophenyl-β-D-glucopyranoside (ρ-NPG) at pH 4.5 and 50 °C. It was found that there was a maximum recovered activity of around 33% (corresponding to hydrolytic activity of 0.48 U/mL) in a spacer/enzyme ratio of 4.69 (mg/mg) using 25.5 mM glutaraldehyde. The optimal temperature and pH conditions for the soluble enzyme were 60 °C and 4.5, respectively, while those for CLEAs of β-glucosidase were between 50 and 65 °C and pH 3.5 and 4.0. These results reveal that the immobilized enzyme is more stable in a wider pH and temperature range than its soluble form. Furthermore, an improvement was observed in thermal stability after immobilization. After 150 days at 4 °C, the heterogeneous biocatalyst retained 80% of its original activity, while the soluble enzyme retained only 10%. The heterogeneous biocatalyst preparation was also characterized by TG/DTG and FT-IR analyses that confirmed the introduction of carbon chains via cross-linking. Therefore, the immobilized biocatalyst prepared in this study has improved enzyme stabilization, and it is an interesting approach to preparing heterogeneous biocatalysts for industrial applications.