(General session) Environment［Wed. Sep 13, 2023 AM Room-5］

[2501-04-01] [Student presentation: Master’s course] Biological Immobilization of Oxidizing Enzymes for Enhanced Bioremediation of Toxic Contaminants

○ILHAM MAULIDIN¹, Kazunori Nakashima¹, Ryo Naota¹, Anju Pilakka Veedu¹, Chikara Takano¹, Satoru Kawasaki¹ (1. Hokkaido University)

Chairperson: Chikara Takano (Hokkaido University),

Keywords:Enzyme immobilization, silica-polymerizing enzyme, bioremediation, toxic compound

Rapid urbanization and industrial activities have resulted in the accumulation of toxic contaminants, posing significant risks to the soil and water ecosystem. Toxic compounds such as petroleum hydrocarbons, and pharmaceutical residues contaminated in soil and water sources exceed acceptable levels, leading to environmental and health concerns. Biodegradation using laccase, an oxidizing enzyme capable of degrading various toxic compounds, has gained attention for environmental remediation. Immobilization of oxidizing enzymes such as laccase on silica matrix holds promise for improving stability, efficiency, and reusability, thereby advancing biodegradation and environmental remediation. However, most immobilization techniques often cause inactivation of enzymes under harsh conditions with reactive reagents. This study introduces a novel immobilization approach using silicatein, a silica-polymerizing enzyme acting as a catalyst in immobilizing laccase onto silica beads, forming a protective silica layer to enhance the laccase stability. The efficiency of this approach was evaluated using ABTS (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) as a model substrate. The result revealed that laccase immobilized by silicatein demonstrated improved stability and showed minimal sensitivity to acidic and alkaline pH conditions by retaining over 83% its relative activity at neutral pH and 46% relative activity under alkaline pH condition and exhibited the remarkable efficiency in the conversion of ABTS around 94.4%. In comparison, laccase immobilized without silicatein retained 25% of its initial activity at neutral pH and less than 10% at alkaline pH condition with the conversion efficiency of ABTS achieved the highest point around 30.6%. Notably, the utilization of silicatein in this immobilization strategy offers a simple, environmentally friendly, and highly effective method for fabricating hybrid materials immobilizing enzymes.