Improvement of lipase biochemical properties via a two-step immobilization method: Adsorption onto silicon dioxide nanoparticles and entrapment in a polyvinyl alcohol/alginate hydrogel.
J Biotechnol 2020;
323:189-202. [PMID:
32861701 DOI:
10.1016/j.jbiotec.2020.07.002]
[Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 06/03/2020] [Accepted: 07/04/2020] [Indexed: 12/21/2022]
Abstract
In this study, the factors affecting lipase adsorption onto SiO2 nanoparticles including SiO2 nanoparticles amounts (8, 19 and 30 mg/mL), lipase concentrations (30, 90 and 150 μg/mL), adsorption temperatures (5, 20 and 35 °C) and adsorption times (1, 12.5 and 24 h) were optimized using central composite design. The optimal conditions were determined as a SiO2 nanoparticles amount of 8.5-14 mg/ml, a lipase concentration of 106-116 μg/mL, an adsorption temperature of 20 °C and an adsorption time of 12.5 h, which resulted in a specific activity and immobilization efficiency of 20,000 (U/g protein) and 60 %, respectively. The lipase adsorbed under optimal conditions (SiO2-lipase) was entrapped in a PVA/Alg hydrogel, successfully. FESEM and FTIR confirmed the two-step method of lipase immobilization. The entrapped SiO2-lipase retained 76.5 % of its initial activity after 30 days of storage at 4 °C while adsorbed and free lipase retained only 43.4 % and 13.7 %, respectively. SiO2-lipase activity decreased to 34.43 % after 10 cycles of use, while the entrapped SiO2-lipase retained about 64.59 % of its initial activity. Compared to free lipase, the Km values increased and decreased for SiO2-lipase and entrapped SiO2-lipase, respectively. Vmax value increased for both SiO2-lipase and entrapped SiO2-lipase.
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