sors, antibodies, enzymes, ion channels, nucleic acids or cell based bio-sensors that include microbial cells, tissues, cell receptors and various biologically derived materials. Biosensors or bioreporters are genetically engineered live microbial cells that generate a measurable signal in response to a particular chemical or physical agent in their immediate environment (King, 1990). Thus, biosensors are sensing components that are capable of generating beneficial signals for further processing.
These signals are generated by reporter genes that are activated in response to the physical or chemical agents. Expressions of these genes are recorded as colorimetric, fluorescent, luminescent, chemiluminescent or electrochemical signals. Biosensors are therefore analytical devices that possess biological substances and work through the bio-recognition progression either by way of affinity or through metabolism. The recognized signals are then read through transducers to relay electrical signals. Various categories of biosensors/ bioreporters:
LuxCDABE bioreporters: LuxCDABE bioreporters are used in detection methodologies ranging from the sensing of environmental contaminants to the real-time monitoring of pathogen infections in living mice.
Nonspecific lux bioreporters: Nonspecific lux bioreporters are characteristically used for the detection of chemical toxins. They are engineered for constant bioluminescence. The level of bioluminescence can be correlated to relative levels of toxicity (Hermens, 1985).
Firefly luciferase (Luc): Firefly luciferase catalyzes a reaction that produces visible light in the 550 – 575 nm range. Numerous luc-based bioreporters have been constructed for the detection of a wide array of inorganic and organic compounds of environmental concern.
Uroporphyrinogen (Urogen) III Methyltransferase (UMT): UMT catalyzes a reaction that yields two fluorescent products which produce a red-orange fluorescence in the 590 - 770 nm range when