Optimization in the production of β-galactosidase from Aspergillus niger in cheese whey and purification by aqueous two-phase system
摘要
The enzyme β-galactosidase is widely used in industrial processes, especially in the development of lactose-free or reduced products. Therefore, the objective of this study was to define the best fermentation conditions for the production of β-galactosidase from Aspergillus niger in cheese whey (CW) and to evaluate the purification of this enzyme through an Aqueous Two-Phase System (ATPS) composed of polyethylene glycol (PEG) and potassium phosphate. To verify the synergistic effects of different carbon and nitrogen sources, pH, and temperature on the production and optimization of the enzyme, a Factorial Design followed by a Rotational Central Composite Design (RCCD) was used. The highest activity was 50.30 U mL− 1 using the RCCD with CW (20% v/v) supplemented with lactose (13 g L− 1), yeast extract (7.5 g L− 1), and peptone (5 g L− 1), in a medium at 35 °C and pH 5.0. The composed of PEG 1500 g mol− 1 (20% w/w) and potassium phosphate (10% w/w) at pH 7.0 is the best condition to partially purify this enzyme, allowing a purification factor of 4.53, with a partition coefficient of 6.17 ± 0.40 and yield of 92.54%. These results demonstrate the possibility of using an ATPS composed of PEG-phosphate to purify a β-galactosidase from Aspergillus niger produced in CW supplemented with carbon and nitrogen sources. The study provides a low-cost and sustainable enzyme production strategy using CW and a simple and efficient purification with ATPS, which may be of great biotechnological interest.