Developing synthetic biology enabled whole cell biosensors

Abstract

Main causative agent for environmental pollution is human activities. Especially with accelerated industrial improvements, many inorganics such as heavy metals or hazardous organic toxic materials are released to the environments via inadequate disposal policies of chemical wastes or accidental spills. These pollutants such as heavy metals could not be degraded easily in the environment. Moreover, tracking heavy metals levels in environmental samples is significant not only for controlling accumulation level of heavy metals in environment but also for human health due to heavy metal accumulation in kidney and liver via food web. Therefore, continuous monitoring of heavy metal pollution is important. For this purpose different kinds of sensor systems including biosensors are widely used. Even these conventional analytic methods are used in a broad range, there are attempts to propose innovative systems with advanced capabilities. Bacterial cells are able to serve as a whole cell biosensor and an analytic device because they naturally have all three layers of conventional sensor systems which are recognition layer, transducer layer and output actuators. Cells can detect changes in the environment and internal conditions via receptors worked as recognition element and placed strictly into membrane or freely in the cytoplasm. Receptors transmit this information into signal transduction pathways which serves as a transducer in the cell. Results of signal transduction pathways such as gene expression, gene repression, differences in concentration of specific molecules are classified as a signal and measured by appropriate device. Here we present our completed whole cell biosensors for urea, uric acid. Additionally we are presenting our results for cloning and expression of transcription factors for heavy metal sensing. As a future aim, we try to develop a fast, reliable and cost effective whole cell biosensor with the intention of sensing many important biomarkers in a conventional blood panel.