Use of silicon dioxide nanoparticles for β-galactosidase immobilization and modulated ethanol production by co-immobilized K. marxianus and S. cerevisiae in deproteinized cheese whey

beta-galactosidase from dairy yeast was immobilized on silicon dioxide based nanoparticles for the hydrolysis of whey. The biocatalyst was checked for the optimal thermal and pH stability. Consequently, the immobilized beta-galactosidase was recycled 15 times for the hydrolysis of lactose (37 degrees C and pH 7.0) without loss of a significant amount of catalytic activity. Almost 91% of lactose hydrolysis was obtained from using concentrated cheese whey. Considering the available approaches for efficient bioconversion of hydrolyzed whey into ethanol, co-immobilization strategy was used using Saccharomyces cerevisiae and Kluyveromyces marxianus for fermentation. Same vessel hydrolysis and fermentation process was employed using silicon dioxide nanoparticles based enzyme immobilization along with co-immobilized yeast cell and provided a maximum ethanol titer of 63.9 g/L on concentrated cheese whey (150 g/L). Hence, the nano-biocatalytic system along with immobilized S.cerevisiae could improve the viability of ethanol production from cheese whey. (C) 2017 Elsevier Ltd. All rights reserved.