Designing A Bacterial Biosensor For Arsenic Detection In Water Solutions

In parallel to continuous development of increasingly more sophisticated physical and chemicalanalytical technologies for the detection of environmental pollutants, there s a progressively more urgentneed also for bioassay which report not only on the presence of a chemical but also on its bioavailabilityand its biological effects. As a partial fulfillment of that need, there s been a rapid development ofbiosensors based on genetically engineered bacteria. Natural water was polluted by arsenic that knowntoxin and carcinogen leaded us to designing a whole cell bacterial biosensor to detect arsenic in liquidsolutions.Methods: In order to construct the biosensor, chromosomal arsR gene and its related promoter/operatorfrom Escherichia coli strain Bl21(DE3), gfp gene as the reporter, plasmid pUC19 as the basic vector anddifferent molecular and genetic engineering techniques such as PCR, gene cloning, etc. were applied tomake the Escherichia coli strain BL21(DE3) act as the arsenic whole cell biosensor. Arsenic detection byusing this biosensor was done by means of microscopy and fluorometery techniques. Strain BL21(DE3)responded mainly to As(III) and As(V) with the lowest detectable concentration being 5 μM during a 3-hours exposure and 1 and 3 μM respectively, with an 6-hours induction period.Results: Our result demonstrate that the nonpathogenic bacterial biosensors developed in the presentstudy could be useful and applicable in determining the bioavailability of arsenic with high sensitivity incontaminated water samples after further optimization, and they suggest a potential for its inexpensiveapplication in field-ready tests.Conclusion: Our success in designing and producing this biosensor, in addition to localizing this usefultechnology, will be a very large and effective step to improve the health status of drinking water, throughto speed up detection of arsenic contamination of water resources. It can also attract lots of academic andindustrial heads for research in this interesting field of science and establish an optimistic future indeveloping biosensor technology in our country.

Keywords:

arsR , Arsenic Contaminant , Biosensor , GFP , Whole Cell Biosensor