Emerging Solutions for in Vivo Biocatalyst Immobilization: Tailor-Made Catalysts for Industrial Biocatalysis

In industry, enzymes are often immobilized to generate more stable enzyme preparations that are easier to store, handle, and recycle for repetitive use. Traditionally, enzymes are bound to inorganic carrier materials, which requires case-to-case optimization and incurs additional labor and costs. Therefore, with the advent of rational protein design strategies as part of bottom-up synthetic biology approaches, numerous immobilization methods have been developed that enable the one-step production and immobilization of enzymes onto biogenic carrier materials often directly within the production host, which we here refer to as in vivo immobilization. As a result, nano- to micro-meter-sized functionalized biomaterials, or biologically produced enzyme immobilizates, are obtained that can directly be used for synthetic purposes. In this Perspective, we provide an overview over established and recently emerging in vivo enzyme immobilization methods, with special emphasis on their applicability for (industrial) biocatalysis. For each approach, we present fundamental working principles as well as advantages and limitations guiding future research avenues toward sustainable applications in the bioindustry