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Optimization of a whole-cell cadmium sensor with a toggle gene circuit

Authors

  • Cindy H. Wu,

    1. Dept. of Chemical and Environmental Engineering, University of California, Riverside, CA 92521
    2. Environmental Toxicology Program, University of California, Riverside, CA 92521
    Current affiliation:
    1. Lawrence Berkeley National Laboratory, One Cyclotron Road. MS 70A-3317, Berkeley, CA 94720
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  • David Le,

    1. Dept. of Chemical and Environmental Engineering, University of California, Riverside, CA 92521
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  • Ashok Mulchandani,

    1. Dept. of Chemical and Environmental Engineering, University of California, Riverside, CA 92521
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  • Wilfred Chen

    Corresponding author
    1. Dept. of Chemical and Environmental Engineering, University of California, Riverside, CA 92521
    • Dept. of Chemical and Environmental Engineering, University of California, Riverside, CA 92521
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Abstract

This work demonstrates improvement of a whole-cell cadmium detection sensor through construction of a gene circuit. A cadmium (II) specific regulatory promoter, PcadR, from Psuedomonas putida 06909, is used in the assembly of a toggle circuit. The circuit contains the cadR promoter fused to lacIq and gfp, and a divergently transcribed tac promoter and cadR. The toggle sensor exhibits lower background fluorescence, and a 20-fold lower detection limit in comparison to a nontoggle gene circuit. The detection limit of the toggle sensor is 0.01 μM (1.12 ppb) cadmium chloride, and tunable with the addition of isopropyl-b-D-thiogalactopyranoside (IPTG). The toggle sensor is highly specific to cadmium (II), and no response is elicited from zinc, lead, manganese, nickel, copper, and mercury. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009

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