Entrapment of Cyanase from Thermomyces lanuginosus Using Biomimetic Silica and Its Application for Cyanate Bioremediation

Cyanate, a toxic product from the chemical oxidation treatment of highly toxic cyanide, can be converted to harmless ammonia and carbon dioxide by cyanase (EC 4.2.1.104). Cyanase from Thermomyces lanuginosus was entrapped in biomimetic silica to improve stability and reusability. After entrapment, the enzyme’s activity increased by two-fold, and the residual activity after 30-min of incubation at 60 °C also increased by two-fold, compared to the free enzyme. After being stored at room temperature for 28 days, the entrapped cyanase retained 79% of the initial activity, while the free form retained 61%. The immobilized cyanase was successfully applied to cyanate detoxification; the co-entrapment of carbonic anhydrase from Sulfurihydrogenibium azorense decreased the amount of bicarbonate necessary for cyanate detoxification by 50%. The cyanate degradation retained 53% of the initial value after the co-entrapped cyanate and carbonic anhydrase were reused five times.