Affiliation:
1. Faculty of Technology and Metallurgy, Belgrade
Abstract
Lipases are very efficient biocatalysts with wide application in synthesis of
important ingredients of food, cosmetics and pharmaceutical products, due to
their capacity to catalyze both, ester synthesis and ester hydrolysis. The
preparation of stable and active immobilized derivatives of lipases is
necessity for their application in industrial enzymatic processes. In this
work, the optimization of lipase from C. rugosa immobilization by microwave
irradiation was performed, since it was previously reported that
immobilization process can be drastically accelerated by means of microwave
irradiation, even resulting with slight increase of lipase activity.
Eupergit?, commercial support with active epoxy groups, was used as
immobilization support. In first stage of our study, the immobilization time
and ionic strength of immobilization buffer were optimized. It was found out
that the highest immobilized activity can be achieved at high ionic strengths
(1 M buffer) after 3 min, while further increase of immobilization time led
to decrease of lipase activity. Then, the immobilized derivative obtained at
optimum conditions was applied in synthesis of amyl isobutyrate in organic
solvent. Key reaction factors (temperature, water concentration, immobilized
lipase concentration, and substrate molar ratio) were optimized using
response surface methodology. The substrate conversion higher above 85% was
achieved in our study. The statistical analysis revealed that each of
analyzed factors had significant effect on yield of ester, with initial
enzyme concentration and substrate molar ratio being the most prominent
factors. The second-order regression model that describes the effect of all
four factors on substrate conversion was established. The optimum values of
factors were: temperature 50?C, initial immobilized enzyme concentration 220
mg ml-1, added water concentration 0.1% (v/v), and molar ratio acid/alcohol
2.5.
Publisher
National Library of Serbia
Subject
General Chemical Engineering,General Chemistry