Determination of the Sensitivity of an Arsenic Biosensor

Abstract

Arsenic (As) is of concern locally and globally in drinking water. Commercial As test kits are available; they are time-consuming, involve multiple steps, and create more toxic waste. We utilized synthetic biology to develop a simple and sensitive As biosensor. Previously, we constructed the biosensor using the Biobrick parts J33201 (an As sensitive promoter); E1010 (red fluorescent protein); and pSB1A3 (an ampicillin resistant destination plasmid). Current efforts focused on testing the viability of the bacterial cells in varied arsenite and arsenate media. Moreover, we wanted to determine the levels of “pinkness” based on the amount of arsenite/arsenate present in the media. Growth conditions were quantified measuring the OD-600 of cell cultures grown up to 20 hours. Results showed the growth of the bacteria containing the different BioBrick plasmids did not grow well under any arsenite and arsenate concentrations used. We also noted that the bacteria was not turning pink in the presence of arsenate/arsenite as had been shown in the past. It was concluded that the effective concentration of ampicillin in the growth medium was lower than expected. The quality of cell lines was also suspect. These issues most likely resulted in reduced growth and protein production. These experiments will be reproduced using a higher concentration of ampicillin and re-tested for As sensitivity. Biological systems are a relatively inexpensive approach to creating easy to