What is a major advantage of immobilized enzymes in industrial biocatalysis?

• A. They cannot be reused.
• B. They are less stable than free enzymes.
• C. They require constant replenishment of substrate.
• D. They are reusable and easier to separate from products.

Answer: (D)

Immobilizing enzymes means anchoring them to a solid support so the enzyme stays in the reactor while the product moves away. This setup lets the same enzyme be used for many reaction cycles, which cuts enzyme costs in industrial processes. After the reaction, the solid-bound enzyme is easy to separate from the liquid product, simplifying purification and reducing contamination of the final product. This easy recovery also makes continuous processing practical, since you can run ongoing streams and reuse the enzyme repeatedly. While some immobilization systems can enhance stability, the big practical win is the combination of reuse and straightforward separation from products, which is not guaranteed by the other options.