Biosensors in bio-processing

• Microbial biosensors are micro-organisms, which produce a reaction upon contact with the substance to be sensed.
• Most biosensors are a combination of biological and electronic devices– often built onto a microchip.
• The biological component might be simply an enzyme or antibody, or even a colony of bacteria, a membrane, neural receptor, or an entire organism.
• The sensor is immobilized on a substrate, its properties changing in response to some environmental effect in a way that is electronically or optically detectable.
• It is then possible to make quantitative measurements of pollutants with extreme precision or to very high sensitivities.
• Immunoassays use labelled antibodies ^{(Complex proteins produced in biological response to specific agents)} and enzymes to measure pollutant levels. If a pollutant is present, the antibody attaches itself to it the; the label making is detectable either through colour change, fluorescence or radio-activity.
• Immunoassays of various types have been developed for the continuous and automated monitoring of pesticides such as dieldrin and parathion. The nature of these techniques, the results of which can be as simple as a colour change, make them particularly suitable for highly sensitive field testing where traditional testing is impractical. Their use is however limited to pollutants, which can trigger can trigger biological antibodies.
• A range of biosensors and bioassays has been developed and applied to bio-processing systems and monitoring of pollutants in the environment. These devices can be based on catalytic elements such as enzymes, micro-organisms (e.g. using bioluminescence), and tissues, or on non-catalytic elements, such as receptages of biosensors, such as high specificity, lack of stability and short lifetime.
• Use of biosensors has considerable potential in pollution prevention, even though specificity presently makes them unsuitable for mass marketing.
• The development of living organism, such as larvae, molluscs, lichens and plants, as pollution indicators might be better suited for commercialization. Multi-purpose bioassays are also promising, for instance, in the development of multi-enzyme systems for the detection of toxic compounds in complex industrial effluents.