The rapidly growing field of microbiome research presents a need for better methods of monitoring gut microbes in vivo with high spatial and temporal resolution. We report a method of tracking microbes in vivo within the gastrointestinal tract by programming them to incorporate non-standard amino acids (NSAA) and labeling them via click chemistry. Using established machinery constituting an orthogonal translation system (OTS), we engineered Escherichia coli to incorporate p-azido-L-phenylalanine (pAzF) in place of the UAG (amber) stop codon. We also introduced a mutant gene encoding for a cell surface protein (CsgA) that had been altered to contain an in-frame UAG codon. After pAzF incorporation and extracellular display, the engineered strains could be covalently labeled via copper-free click reaction with a Cy5 dye conjugated to the dibenzocyclooctyl (DBCO) group. We confirmed the functionality of the labeling strategy in vivo using a murine model. Labeling of the engineered strain could be observed using oral administration of the dye to mice several days after colonization of the gastrointestinal tract. This work sets the foundation for the development of in vivo tracking microbial strategies that may be compatible with non-invasive imaging modalities and are capable of longitudinal spatiotemporal monitoring of specific microbial populations.

Tracking of engineered bacteria <i>In Vivo</i> using non-standard amino acid incorporation

256th National Meeting (2018)

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Tracking of engineered bacteria In Vivo using non-standard amino acid incorporation