Recyclable thermophilic hybrid protein-inorganic nanoflowers for the hydrolysis of milk lactose.

Thermostable β-galactosidase (TmLac) has been immobilized as hybrid inorganic-protein nanoflowers using salts of Cu, Mn, Zn, Co and Ca as the inorganic component. The incorporation efficiency of enzyme into the nanoflowers was higher than 95% for a protein concentration of 0.05 mg/mL. The structure, activity and recyclability of the nanoflowers with different chemical composition were analyzed. Ca, Mn and Co nanoflowers showed a level of lactase activity equivalent to their same content of free enzyme. Cunanoflowers showed only marginal enzyme activity in agreement with the inhibitory effect of this cation on the enzyme. TmLac nanoflowers provide an efficient methodology for enzyme immobilization and recyclability. TmLac-Ca nanoflowers presented the best properties for lactose hydrolysis both in buffered and in milk, and could be reused in five consecutive cycles.