Feruloyl esterase immobilization in mesoporous silica particles and characterization in hydrolysis and transesterification

Artikel i vetenskaplig tidskrift, 2018

Background: Enzymes display high reactivity and selectivity under natural conditions, but may suffer from
decreased efficiency in industrial applications. A strategy to address this limitation is to immobilize the enzyme.
Mesoporous silica materials offer unique properties as an immobilization support, such as high surface area and
tunable pore size.
Results: The performance of a commercially available feruloyl esterase, E-FAERU, immobilized on mesoporous silica
by physical adsorption was evaluated for its transesterification ability. We optimized the immobilization conditions
by varying the support pore size, the immobilization buffer and its pH. Maximum loading and maximum activity
were achieved at different pHs (4.0 and 6.0 respectively). Selectivity, shown by the transesterification/hydrolysis
products molar ratio, varied more than 3-fold depending on the reaction buffer used and its pH. Under all
conditions studied, hydrolysis was the dominant activity of the enzyme. pH and water content had the greatest
influence on the enzyme selectivity and activity. Determined kinetic parameters of the enzyme were obtained
and showed that Km was not affected by the immobilization but kcat was reduced 10-fold when comparing the free
and immobilized enzymes. Thermal and pH stabilities as well as the reusability were investigated. The immobilized
biocatalyst retained more than 20% of its activity after ten cycles of transesterification reaction.
Conclusions: These results indicate that this enzyme is more suited for hydrolysis reactions than transesterification
despite good reusability. Furthermore, it was found that the immobilization conditions are crucial for optimal
enzyme activity as they can alter the enzyme performance.