Comparative study of thermostabilty and ester synthesis ability of free and immobilized lipases on cross linked silica gel

Abstract

A novel support has been utilized for immobilization of lipase, which was prepared by amination of silica with ethanolamine followed by cross linking with glutaraldehyde. Lipases from Rhizopus oryzae 3562 and Enterobacter aerogenes were immobilized on activated silica gel, where they retained 60 and 50% of respective original activity. The thermal stability of the immobilized lipases was significantly improved in comparison to the free forms while the pH stability remained unchanged. E. aerogenes and R. oryzae 3562 lipases retained 75 and 97% of respective initial activity on incubation at 90 degrees C, whereas both the free forms became inactive at this temperature. The conversion yield of isoamyl acetate was found to be higher with the immobilized fungal (90 vs. 21%) and bacterial lipases (64 vs. 18%) than the respective free forms. Immobilized R. oryzae 3562 lipases retained 50% activity for isoamyl acetate synthesis up to ten cycles whereas it was eight cycles for E. aerogenes.

Immobilization of Beauveria bassiana Lipase on Silica Gel by Physical Adsorption

“…These results suggested that the nature of adsorption of B. bassiana lipase on silica gel was hydrophobic probably by interfacial activation (Fernandez-Lorente et al 2008). Operational stability Adsorbed lipase shows a great reuse capacity in organic solvents because of the less leakage of enzyme from support (Kumari et al 2008;Doukyu and Ogino 2010). The operational stability can make the process feasible despite the high costs of production, purification and immobilization of enzymes (Mateo et al 2007).…”

“…This reduction of activity probably occurred due to lipase desorption from silica gel during repeated use. Kumari et al (2008) reported 90% of activity retention after four cycles of isoamyl acetate synthesis by Enterobacter aerogenes lipase immobilized on silica gel by cross-link method. …”

“…Furthermore, immobilized enzymes generally show increased stability under operational condition, heat, organic solvent and extreme pH values (Mateo et al 2007; Kumari et al 2008;Nicolic et al 2009). The support for immobilization must be carefully selected because its characteristics (nature, reactive group and interaction forms with enzymes) can affect the activity of the enzyme (Knezevic et al 2004).…”

Comparative studies of the stability of free and immobilized inulinase from Kluyveromyces marxianus NRRL Y-7571 in aqueous-organic solutions

“…An alternative to avoid the direct contact between enzyme and organic solvent is the recovering of the enzyme by immobilization on different inert supports. Besides, the enzyme immobilization offers other advantages over the free enzymes, such as the possibility of reuse, continuous operations and higher stability to temperature, pH and organic solvents (Kumari et al, 2008).…”

Assessment of fructooligosaccharides production from sucrose in aqueous and aqueous-organic systems using immobilized inulinase from Kluyveromyces marxianus NRRL Y-7571

“…However, most enzymes including inulinase are easy to denature and lose their catalytic activities in the presence of organic solvents. To overcome these shortcomings, it is interesting to use immobilized enzymes, which may offer advantages over free enzymes such as the possibility of reuse, continuous operations, better control of reactions, and improved stability of temperature, pH, and organic solvents (KUMARI et al, 2008). Recent studies showed that the use of immobilized inulinase enhance temperature and pH stability in buffer solutions (SANTOS; OLIVEIRA; and allow us to reuse the same enzyme for several cycles (SINGH; DHALIWAL; PURI , 2007).…”