Implementation of combinatorial genetic and microenvironmental engineering to microbial-based field-deployable microbead biosensors for highly sensitive and remote chemical detection

Abstract

Bioreporters, microbial species genetically engineered to provide measurable signals in response to specific chemicals, have been widely investigated as sensors for biomedical and environmental monitoring. More specifically, the biore-porter encapsulated within a biocompatible material, such as hydrogel that can provide suitable microenvironment for their prolonged activity as well as efficient scalable production, has been viewed as a more broadly applicable mode of biosensors. In this study, alginate-based microbeads encapsulated with the bacterial bioreporter capable of expressing green fluorescence protein in response to nitro compounds (e.g. TNT and DNT) are developed as biosen-sors. In order to significantly enhance the sensitivity of the microbial-based microbead biosensors, “multifaceted” modification strategies are simultaneously employed; (1) multiple genetic modifications of the bioreporter, (2) tuning the physicomechanical properties of the encapsulating microbeads, (3) controlling the initial cell density within the microbeads, and (4) enrichment of nitro compounds inside microbeads via functional nanomaterials. These microbial and microenvironmental engineering approaches combine to significantly enhance the sensing capability, even allow-ing highly sensitive remote detection under low vapor phase. Thus, the strategy developed herein is expected to con-tribute to various cell-based biosensors.