N butyryl dl homoserine lactone

E. coli Nissle 1917 was used for experimentally assaying sensors, genetic
gates, and circuits. E. coli NEB
5-alpha (New England Biolabs) was used for cloning. E. coli NEB 10-beta (New England Biolabs) was
used to compare sensor and NOT gate response functions to EcN. Genetic
circuits and sensors were assayed in M9 minimal media (Sigma-Aldrich;
6.78 g/L Na₂HPO₄, 3 g/L KH₂PO₄, 1 g/L NH₄Cl, 0.5 g/L NaCl final concentration)
with 0.34 g/L thiamine hydrochloride (Sigma-Aldrich), 0.2% Casamino
acids (Acros), 2 mM MgSO₄ (Sigma-Aldrich), 0.1 mM CaCl₂ (Sigma-Aldrich), and 0.4% d-glucose (Sigma-Aldrich).
Antibiotics used to select for circuit plasmids were 50 μg/mL
kanamycin (GoldBio), and 100 μg/mL spectinomycin (GoldBio).
The inputs used for the sensor promoters were isopropyl β-d-1-thiogalactopyranoside (GoldBio), anhydrotetracycline hydrochloride
(Sigma-Aldrich), l-arabinose (Sigma-Aldrich), choline chloride
(Sigma-Aldrich), gamma-aminobutyric acid (Sigma-Aldrich), N-butyryl-dl-homoserine lactone (Sigma-Aldrich),
3-oxohexanoyl-l-homoserine lactone (Sigma-Aldrich), N-(3-oxododecanoyl)-l-homoserine lactone (Sigma-Aldrich),
and N-(3-hydroxytetradecanoyl)-dl-homoserine
lactone (Sigma-Aldrich). The stock solutions were aqueous solutions,
except those used for HSLs and aTc. The stock solutions for HSLs were
dissolved in 100% dimethyl sulfoxide, and aTc was dissolved in 100%
ethanol.