Metabolic engineering of synthetic cell-free systems: Strategies and applications

Recently, the focus of biotechnological research has shifted towards the improvement of biological processes. Among the various approaches to achieve this goal, the use of cell-free technology is receiving considerable attention because it offers several economic and technical benefits. This technology improves biological processes in several ways, leading to enhanced efficacy, stability, specificity, and selectivity, as well as allowing reconstruction of target metabolic pathways. However, the adaptation of this technology to large-scale industrial processes remains a major challenge. This review describes the major constrains of whole-cell-based biological processes and how cell-free systems have been used to overcome such limitations. Furthermore, the shortcomings of conventional cell-free systems and possible solutions involving developments in immobilization technology are discussed. Finally, we illustrate the development of synthetic metabolic systems using the principles of metabolic engineering and discuss their possible advantages in the production of biofuels and bioproducts. In short, this review describes the fundamentals of and provides new insights into cell-free and immobilization technologies for the improvement of synthetic metabolic systems.