Bacterial bioreporter detection of arsenic associated with iron oxidesElectronic supplementary information (ESI) available: Additional data pertinent to the calibration of the bioreporter system and TEM data of precipitate samples. See DOI: 10.1039/c8em00071a

Bacterial bioreporters are engineered microorganisms that have found recent application as a low-cost method of detecting arsenic (As) in environmental systems. However, no assessment exists of bioreporter detection of particle-bound As. We applied an Escherichia coli -based bioreporter to assess the bioavailability of As( v ) adsorbed by goethite (α-FeOOH), 2-line ferrihydrite and As( v ) co-precipitated with Fe( iii ). We found that As( v ) bound to the surface of crystalline goethite was not detected by the bioreporters, which contrasted sharply the 50% detection of As( v ) adsorbed by ferrihydrite. In addition, the presence of Ca 2+ caused a systematic decrease in the bioreporter-detected As( v ) fraction in the ferrihydrite samples. For co-precipitated As( v )-Fe( iii ) samples, we found a similar bioreporter-detected As( v ) fraction (