Immobilization of Baeyer-Villiger monooxygenase from acetone grown Fusarium sp

Bioinspired Nanochitin-Based Porous Constructs for Light-Driven Whole-Cell Biotransformations

Solid-state photosynthetic cell factories (SSPCFs) are a new production concept that leverages the innate photosynthetic abilities of microbes to drive the production of valuable chemicals. It addresses practical challenges such as high energy and water demand and improper light distribution associated with suspension-based culturing; however, these systems often face significant challenges related to mass transfer. The approach focuses on overcoming these limitations by carefully engineering the microstructure of the immobilization matrix through freeze-induced assembly of nanochitin building blocks. The use of nanochitins with optimized size distribution enabled the formation of macropores with lamellar spatial organization, which significantly improves light transmittance and distribution, crucial for maximizing the efficiency of photosynthetic reactions. The biomimetic crosslinking strategy, leveraging specific interactions between polyphosphate anions and primary amine groups featured on chitin fibers, produced mechanically robust and wet-resilient cryogels that maintained their functionality under operational conditions. Various model biotransformation reactions leading to value-added chemicals are performed in chitin-based matrix. It demonstrates superior or comparable performance to existing state-of-the-art matrices and suspension-based systems. The findings suggest that chitin-based cryogel approach holds significant promise for advancing the development of solid-state photosynthetic cell factories, offering a scalable solution to improve the efficiency and productivity of light-driven biotransformation.

Immobilization of Thermoplasma acidophilum Glucose Dehydrogenase and Isocitrate Dehydrogenase Through Enzyme-Inorganic Hybrid Nanocrystal Formation

The development of green catalysts, specifically biocatalysts, is crucial for building a sustainable society. To enhance the versatility of biocatalysts, the immobilization of enzymes plays a vital role as it improves their recyclability and robustness. As target enzymes to immobilize, glucose dehydrogenases and carboxylases are particularly important among various kinds of enzymes due to their involvement in two significant reactions: regeneration of the reduced form of coenzyme required for various reactions, and carboxylation reactions utilizing CO2 as a substrate, respectively. In this study, we immobilized Thermoplasma acidophilum glucose dehydrogenase (TaGDH) and T. acidophilum isocitrate dehydrogenase (TaIDH) using a previously reported method involving the formation of enzyme-inorganic hybrid nanocrystals, in the course of our continuing study focusing on carboxylation catalyzed by the free form of TaGDH and TaIDH. Subsequently, we investigated the properties of the resulting immobilized enzymes. Our results indicate the successful immobilization of TaGDH and TaIDH through the formation of hybrid nanocrystals utilizing Mn2+. The immobilization process enhanced TaIDH activity, up to 211%, while TaGDH retained 71% of its original activity. Notably, the immobilized TaGDH exhibited higher activity at temperatures exceeding 87 °C than the free TaGDH. Moreover, these immobilized enzymes could be recycled. Finally, we successfully utilized the immobilized enzymes for the carboxylation of 2-ketoglutaric acid under 1 MPa CO2. In conclusion, this study represents the first immobilization of TaGDH and TaIDH using the hybrid nanocrystal forming method. Furthermore, we achieved significant activity enhancement of TaIDH through immobilization and demonstrated the recyclability of the immobilized enzymes.