Evaluation of bioavailable arsenic and remediation performance using a whole-cell bioreporter

The traditional method of evaluating the effects of soil contaminants on living organisms by measuring the total amount of contaminant has been largely inadequate, in part because testing contamination levels is hindered in real samples. Here we report a novel strategy for testing arsenic (As) bioavailability in soil samples by direct (in vivo) and indirect (in vitro) measurement using an Escherichia coli-based whole-cell bioreporter (WCB). The WCB was used to test As-amended Landwirtschaftliche Untersuchungs und Forschungsanstalt soils as well as field soils collected from a smelter area under remediation in order to evaluate the efficiency of bioavailable As removal. The percentage of bioavailable As in amended and field soils was 5.8% (range: 4.9%-7.6%) and 0.6% (0.08%-1.09%) of total As, respectively. In contaminated soils, total As was decreased, whereas bioavailable As was slightly increased after soil washing. These results emphasize the importance of considering ecotoxicological aspects of soil remediation; to this end, the WCB is a useful tool for evaluating the efficiency of soil remediation by assessing bioavailability along with the total amount of contaminant present.