Hydrogel-Based Biocontainment of Bacteria for Continuous Sensing and Computation

Abstract

Genetically modified microorganisms (GMMs) can enable a wide range of important applications, including environmental sensing, precision therapeutics, and responsive materials. However, containment of GMMs to prevent environmental escape and satisfy regulatory requirements is a bottleneck for real-world use. While biochemical strategies have been developed to restrict unwanted growth and replication of GMMs in the environment, there is a need for deployable physical containment technologies to achieve redundant, multi-layered, and robust containment. In addition, form factors that enable easy retrieval would be useful for environmental sensing. To address this challenge, we developed a hydrogel-based encapsulation system for GMMs that incorporates a biocompatible multilayer tough shell and an alginate-based core. This DEployable Physical COntainment Strategy (DEPCOS) allows no detectable GMM escape, bacteria to be protected against environmental insults including antibiotics and low pH, controllable lifespan, and easy retrieval of genetically recoded bacteria. To highlight the versatility of a DEPCOS, we demonstrate that robustly encapsulated cells can execute useful functions, including performing cell-cell communication with other encapsulated bacteria and sensing heavy metals in water samples from the Charles River. We envision that our multilayered physical and chemical containment strategy will facilitate the realization of a wide range of real-world applications for "living" biosensors.