Wood cellulignin as an alternative matrix for enzyme immobilization.

The objective of this work was to select an efficient methodology for preparing active samples of Candida rugosa lipase immobilized in wood cellulignin, to be applied in hydrolysis and ester reactions. For this purpose, lipase was immobilized in the matrix by physical adsorption (pure cellulignin) and covalent binding (activated cellulignin with glutaraldeyde or carbonyldiimidazole [CDI]) in the presence or absence of polyethylene glycol (PEG) (Molecular mass of 1500 Daltons) as stabilizing agent. The activating agent and the presence of PEG-1500 in the immobilization procedure showed a strong influence on enzyme retention in the support. The values for enzyme retention ranged from 20 to 68%, and the highest yield was obtained when the enzyme was immobilized in cellulignin activated with CDI in the presence of PEG-1500. This immobilized derivative presented high hydrolytic (193.27 microM/[mg.min]) and synthetic (522.92 microM/[g.min]) activities when compared with those obtained by other techniques. The superiority of this immobilized system was confirmed by additional analyses, such as infrared spectroscopy and elemental analysis, which demonstrated an appropriate enzyme fixation and the highest level of protein incorporation in the support. Further information on the immobilized derivative was obtained by assessing the recycle potential in both aqueous and nonaqueous media.

Immobilization of lipase on chitin and its use in nonconventional biocatalysis.

Chitin was functionalized with hexamethylenediamine followed by glutaraldehyde activation, and its capacity to bind Candida rugosa lipase was investigated. The loading of 250 units g(-1) support showed to be effective, resulting in a uniform enzyme fixation with high catalytic activity. Both free and immobilized lipases were characterized by determining the activity profile as a function of pH, temperature, and thermal stability. For the immobilized lipase, the influence of the reaction temperature and substrate polarity in nonconventional biocatalysis was also analyzed. Production of butyl esters was found to be dependent on the substrate partition coefficient, which accounts the greatest value for the system butanol and butyric acid. The highest enzyme activity was found for the system butanol and caprylic acid at a reaction temperature of 40 degrees C. Under such conditions, the operational stability tests indicated that a small enzyme deactivation occurs after 12 batches, revealing a biocatalyst half-life of 426.7 h.