Sensitivity of Synthetic Biological Circuits to Environmental Conditions

The field of synthetic biology enables the design of complex genetic circuits which can be adapted to solve technical challenges in a wide variety of disciplines. To facilitate rapid engineering, it is desirable for these systems to be modular and transferable. Currently, however, their characterization in varying environmental conditions is limited, with most synthetic circuits having been developed and characterized under single, ideal conditions. In metabolic engineering and industrial biotechnology, the diversity of the products, organisms, and environments necessitates systems that are well characterized, functional, and robust towards changes in these variables. In this work, we determine the functionality of different implementations of the genetic toggle switch, one of the seminal feats of synthetic biology. By exposing different toggle switches to varying environmental conditions, we have shown that these systems are heavily dependent on their environment, limited not only to media composition but also oxygen availability. In addition to these conditions affecting the efficiency of these systems, they can also fully inactivate them, causing them to behave unpredictably. An understanding of these synthetic biological circuits and their activity in different environments is crucial to ensure their modularity, while increasing their complexity and allowing their adoption and evolution within new fields.