Optimization of a Whole-Cell Cadmium Sensor with a Toggle Gene Circuit

摘要

This work demonstrates improvement of a whole-cell cadmium detection sensor through construction of a gene circuit. A cadmium (II) specific regulatory promoter,P_(cad)R,from Psuedomonas putida 06909,is used in the assembly of a toggle circuit. The circuit contains the cadR promoter fused to lacI~q 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-thi-ogalactopyranoside (IPTG). The toggle sensor is highly specific to cadmium (II),and no response is elicited from zinc,lead,manganese,nickel,copper,and mercury.