Development of fluorescent whole-cell bacterial bioreporters for detection of inorganic arsenic and cadmium

Elçin, Evrim
Environmental heavy metal contamination in many regions of the world is a serious problem of ecological health. Fast and constant monitoring of their levels is significant for both preventing their accumulation and taking an immediate action for removal. As an alternative approach to standard laboratory techniques, various biosensor systems for detection of heavy metals have been proposed. Bacterial biosensors hold great promise for in-field detection of heavy metals. In this study, two different whole cell Escherichia coli bioreporter strains were developed for detection of inorganic arsenic and cadmium. In their presence, reporter gene expression increases which is detected as fluorescent signal later interpreted as a measure of available metal level in sample. Following cloning studies, arsenic and cadmium bacterial bioreporter strains were characterized for their metal specificity and detection limits by using different media and induction plans. In liquid assays, arsenic bioreporter could detect arsenite and arsenate at 10 μg/L after 2 hours, and cadmium bioreporter could detect cadmium of 2 μg/L after 1.5 hours of induction. Additionally, the arsenic bioreporter could estimate the bioavailable arsenic level in contaminated groundwater sample. To be integrated into a portable device, immobilization of arsenic bacterial bioreporter was investigated using agar and alginate biopolymers. Entrapment parameters of polymer concentration and cell density were evaluated. Immobilized cells were characterized for their metal specificity and detection limits by using different media. Agar and alginate immobilized bioreporter systems could detect arsenite and arsenate of 25 μg/L and 150 μg/L within 5 hours and 2 hours, respectively. The results demonstrated that these bacterial arsenic and cadmium bioreporter strains are applicable in determining the environmentally safe concentrations of these two most abundant heavy metals.


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Heavy metal pollution, which is growing and threatening the health of all living things as well as human health, can lead to serious lifelong consequences. It is very important to detect and monitor these heavy metals that cause environmental pollution. In addition to traditional laboratory techniques, the use of bacterial biosensors to detect heavy metals has come into focus. In addition, it is known that the immobilization of these bacterial biosensors is more advantageous in many respects, such as being ...
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Environmental pollution caused by heavy metal exposure has detrimental effects on human health. For the reclamation of polluted areas, bacteria have been used in remediation. For those bioremediation attempts, finding the appropriate bacterial strains is an important issue. In their environment, bacteria may exist close to the source of heavy metals. Sudden exposure to high concentrations of the heavy metal may trigger quick response mechanisms to ensure survival. On the other hand, bacteria may live at a d...
Citation Formats
E. Elçin, “Development of fluorescent whole-cell bacterial bioreporters for detection of inorganic arsenic and cadmium,” Thesis (Ph.D.) -- Graduate School of Natural and Applied Sciences. Biotechnology., Middle East Technical University, 2019.