An extracellular alkaline lipase of a thermo tolerant Bacillus coagulans BTS-3 was immobilized onto glutaraldehyde activated Nylon-6 by covalent binding. Under optimum conditions, the immobilization yielded a protein loading of 228 microg/g of Nylon-6. Immobilized enzyme showed maximum activity at a temperature of 55 degrees C and pH 7.5. The enzyme was stable between pH 7.5-9.5. It retained 88% of its original activity at 55 degrees C for 2h and also retained 85% of its original activity after eight cycles of hydrolysis of p-NPP. Kinetic parameters Km and Vmax were found to be 4mM and 10 micromol/min/ml, respectively. The influence of organic solvents on the catalytic activity of immobilized enzyme was also evaluated. The bound lipase showed enhanced activity when exposed to n-heptane. The substrate specificity of immobilized enzyme revealed more efficient hydrolysis of higher carbon length (C-16) ester than other ones.
"The epoxy-activated carrier can slowly multipointedly covalently attach to nucleophiles on the enzyme (e.g., amino, thiol, and hydroxyl groups) after adsorption  . Activation of aminated carrier with glutaraldehyde could form Schiff bases with amine groups of enzyme and achieve multipoint covalent attachment    "
[Show abstract][Hide abstract] ABSTRACT: To improve the reusability and organic solvent tolerance of microbial lipase and expand the application of lipase (hydrolysis, esterification, and transesterification), we immobilized marine microbial lipase using different methods and determined the properties of immobilized lipases. Considering the activity and cost of immobilized lipase, the concentration of lipase was fixed at 2 mg/mL. The optimal temperature of immobilized lipases was 40°C and 5°C higher than free lipase. The activities of immobilized lipases were much higher than free lipase at alkaline pH (more than 50% at pH 12). The free lipase lost most activity (35.3%) and immobilized lipases retained more than 46.4% of their initial activity after 3 h heat treatment at 70°C. At alkaline pH, immobilized lipases were more stable than free lipase (more than 60% residue activity at pH 11 for 3 h). Immobilized lipases retained 80% of their activity after 5 cycles and increased enzyme activity (more than 108.7%) after 3 h treatment in tert-butanol. Immobilization of lipase which improved reusability of lipase and provided a chance to expand the application of marine microbial lipase in organic system expanded the application range of lipase to catalyze hydrolysis and esterification in harsh condition.
"Some synthetic polymers used as enzyme supports are stated as follows: polyvinyl chloride that prevents enzyme, cyclodextrin glucosyltransferase from thermal inactivation; polyurethane microparticles derived from polyvinyl alcohol and hexamethyl diisocyanate in the ratio of 1:3 with high enzyme loading and efficiency; UV-curable methacrylated/fumaric acid-modified epoxy that is proposed to be useful for industrial applications; polyaniline in two different forms, viz. emeraldine salt and emeraldine base powder used for covalent binding of α- amylase; glutaraldehyde-activated nylon for immobilizing lipase and UV-activated polyethylene glycol having high porosity employed for wastewater treatment (Abdel-Naby 1999; Kahraman et al. 2007; Pahujani et al. 2008; Romaskevic et al. 2010; Xiangli et al. 2010; Ashly et al. 2011). "
[Show abstract][Hide abstract] ABSTRACT: The current demands of the world’s biotechnological industries are enhancement in enzyme productivity and development of novel techniques for increasing their shelf life. These requirements are inevitable to facilitate large-scale and economic formulation. Enzyme immobilization provides an excellent base for increasing availability of enzyme to the substrate with greater turnover over a considerable period of time. Several natural and synthetic supports have been assessed for their efficiency for enzyme immobilization. Nowadays, immobilized enzymes are preferred over their free counterpart due to their prolonged availability that curtails redundant downstream and purification processes. Future investigations should endeavor at adopting logistic and sensible entrapment techniques along with innovatively modified supports to improve the state of enzyme immobilization and provide new perspectives to the industrial sector.
"Nevertheless, this problem can be overcome by enzyme immobilization , which enhances thermal and operational stabilities , ease of handling, and prevention of aggregation and autolysis. Besides, immobilized lipases (IE) on solid support allow recoverability and reuse thus significantly reducing operational costs of industrial processes     . An immobilization process involving hydrophobic binding of lipases by adsorption has proved success due to the enzyme affinity for water/oil interfaces   . "
[Show abstract][Hide abstract] ABSTRACT: This study aimed to develop an optimal continuous process for lipase immobilization in a bed reactor in order to investigate the possibility of large-scale production. An extracellular lipase of
(strain HB85A) was immobilized by adsorption onto a polystyrene-divinylbenzene support. Furthermore, response surface methodology (RSM) was employed to optimize enzyme immobilization and evaluate the optimum temperature and pH for free and immobilized enzyme. The optimal immobilization conditions observed were 150 min incubation time, pH 4.76, and an enzyme/support ratio of 1282 U/g support. Optimal activity temperature for free and immobilized enzyme was found to be 68°C and 52°C, respectively. Optimal activity pH for free and immobilized lipase was pH 4.6 and 6.0, respectively. Lipase immobilization resulted in improved enzyme stability in the presence of nonionic detergents, at high temperatures, at acidic and neutral pH, and at high concentrations of organic solvents such as 2-propanol, methanol, and acetone.
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