Microbial Biosensors: Tools for Detection and Monitoring of Environmental Pollutants

Environmental pollution is a worldwide problem and it is necessary to develop sensitive, effective and inexpensive methods, which can efficiently monitor and determine the level of hazardous contaminant in the environment. Microbial biosensors are analyticaldevices for quantitative and qualitative determination of environmental pollutants and these devices integrate microorganisms with a transducer to generate a measurable signal proportional to the concentration of the analytes. Biosensors are being developed for different applications, including environmental monitoring, food processing and quality control of food, agriculture and medical applications. Recently, genetically engineered microorganisms based on fusing of the lux, luc, gfp or lacZ gene reporters to an inducible gene promoter have been widely applied to assay toxicity. The biological recognition element responds to the target compound and the transducer converts the biological response to a detectable signal (bioluminescence, green fluorescent protein and production of blue color in presence of X-gal; respectively), which can be measured and correlated with the analyte concentration. The present approach is based on the use of bacteria that are genetically engineered so that a measurable signal is produced when the bacteria are in contact with the toxicant. Conventionally, many samples have to be analyzed in order to detect and identify the environmental pollutants and their dangerous effects. Bioreporters provide an alternative approach for identifying of soil and water pollutants. Reporter genes are widely used as tools for quantification and detection of biosensors as specific and sensitive devices for measuring biologically relevant concentrations of pollutants.