Fig. 5
From: Engineered live bacteria as disease detection and diagnosis tools
A Rational design of an AND gate. (i) An AND-gate genetic circuit produces the gfp reporter output only when both PBAD and Psal are induced. (ii) A quantitative model for the design of ribosomal binding sites (RBS) predicts the accuracy of circuits logic (fitness) as a function of ΔGtot of the PBAD promoter’s RBS sequence (blue line). The experimental data (circles) are in good agreement with the model. (iii) The GFP expression level in response to combinations of arabinose (0.0, 1.3 × 10−3, 8.3 × 10−2 and 1.3 mM) and salicylate (0.0, 6.1 × 10−4, 3.9 × 10−2 and 0.62 mM) for the optimal (ΔGtot = -1.48 kcal/mol) and 3 other RBS designs. Reprinted with permission from [237]. B Emergent behavior of engineered quorum-sensing bacteria is regulated by localized decision-making. Autoinducer signal concentration field for two sub-populations at (i) 98% and 2% and (ii) 54% and 46% ratios. Green indicates steady-state activation, and black (2%) indicates steady-state inactivation. Average intracellular GFP concentration for agents of the larger (iii) and smaller (iv) populations vs. time for different population ratios. Reprinted with permission from [241]. C Representation of Gram-negative and Gram-positive bacterial uptake of gold nanoparticles for aggregation-enhanced imaging and antibacterial effect. Gold nanoparticle uptake enables dual mode (fluorescence imaging (FI) and photoacoustic imaging (PAI)) and combinatorial (photothermal therapy (PTT) and photodynamic therapy (PDT)) therapy. Reprinted with permission from [157]. D Schematic diagram of intelligent, responsive bacteria for diagnosis and therapy (i-ROBOT) system for diagnosis, recording, and treatment of colitis. (i) Schematic of the engineered components and pathways. (ii) i-ROBOT senses the colitis biomarker thiosulfate, produces real-time (fluorescence) signal, and records the detection event (genomic molecular recording and colorimetric output). Thiosulfate also regulates the drug-protein AvCystatin release to treat mouse colitis. Reprinted with permission from [23]