Biotechnology and Bioinformatics (1+1)

6.5.2. Advantages (bioavailability, etc) and concept

Biosensors measure the bio-available concentration of the contaminant they are designed to detect. In a biosensor, the expression of a reporter gene is controlled by a genetic regulatory unit (receptor), which responds to the given analyte (heavy metals, genotoxic elements etc), using a receptor–reporter concept. Bioavailability is a critical issue in determining metal toxicity the potential for metal bioaccumulation, and the efficiency of bioremediation of metal-contaminated environments. Regulatory genes responsible for induction of specialized microbial systems can be considered sensitive receptors specifically responding to a target compound at physiologically significant concentrations. Bioluminescence genes (lux) have been recognized as a convenient reporter system. Several lux operons have been cloned from a number of luminescent bacteria and studied in detail, and their utility as the reporter part of biosensors has been demonstrated for hydrocarbons and mercurial compounds.

The greatest advantage of biosensors is their ability to detect the bio-available fraction of the contaminant, as opposed to the total concentration, which allows for a more accurate assessment of the site and the potential risks involved. Biosensors are also fast, less expensive and less labor intensive than other traditional methods such as atomic absorption spectrometry, inductively coupled atomic electron spectrometry, and sequential extraction procedure. The results obtained from biosensors are compatible with and comparable to chemical analysis, while being free of chemical extractions and analytical procedures. Biosensors can also be more sensitive than chemical methods. They are particularly appealing for field work or in situ analysis, since the procedure for using biosensors does not involve the bulky, fragile equipment or specialized training that most analytical methods require.