Sol-Gel of Rice Husk Ash: Entrapment of Alkaliphilic Lipase from Pseudomonas sp. KLB1

Abstract

Entrapment in sol-gel from rice husk ash was established by immobilization of alkali lipase produced by Pseudomonas sp. KLB1 lipase. The enzyme was strongly immobilized by entrapment in neutral sol- gel of rice husk ash. It was optimally active at 60°C and pH 9. Its activity was constant in the
medium pH 9 under temperature 70°C for 1 hr. The immobilized lipase was activated by Ca²⁺, K⁺, Na⁺, EDTA and ascorbic acid but inhibited by Fe²⁺, Mn²⁺, Co²⁺, and KI. Both Ca²⁺,and Na⁺ were mainly found in rice husk ash and xerogel. The effective concentration of CaCl₂ and NaCl on the enzyme
activation were 60 mM and 20mM, respectively. According to reusability, it was applied into the hydrolysis of p-nitrophenyl palmitate by 12 times which lost 50% activity. The Km, and Vmax of p-NPP hydrolysis catalyzed by the entrapped enzyme were 7.43 ×10^–2 mM, and 1.94 ×10^-5mM s^-1, respectively, whilst by the free enzyme were 21.69 mM, and 3.90 × 10^-3 mM s^-1, respectively.