[Construction of an Escherichia coli strain for sensitive detection of arsenite ion in water].

In order to construct an Escherichia coli strain with high sensitivity and specificity to detect arsenic ion using fluorescence as reporter, a sensitive strain to arsenic ion was obtained by knocking out the gene arsB that acts as an arsenic efflux pump. The pET28b vector containing arsenite detecting cassette Pars-arsR-egfp was constructed and then transformed into arsB deleted mutant. Measuring conditions of this constructed whole-cell biosensor were optimized and its linear concentration range, limit of detection and specificity were determined. This modified biosensor was much more sensitive than that using wild-type strain as host. The optimal detection range of As³⁺ concentration was 0.013 to 42.71 μmol/L, and the limit concentration of detection was as low as 5.13 nmol/L. Thus we successfully improved the sensitivity of arsenite detecting biosensor by modification of E. coli genome, which may provide useful strategies for development and optimization of microbial sensors to detect heavy metals.