ABSTRACT
A “biosensor” is a system that detects the presence of a substrate using a biological component which then provides a signal that can be quantifi ed (Gu et al. 2004). BWBs employ live cells (usually genetically engineered bacteria) as detection elements and they have two unique advantages: providing information on toxicity and bioavailability, which directly link environmental contamination to human health risk. Most environmental samples are mixtures of complex contaminants. The additive, antagonistic, and synergistic effects caused by complex physical or chemical interactions would make the risk assessment unpredictable if only chemical analysis (e.g. GC-MS or HPLC) were used to estimate the toxicity and bioavailability of contaminated samples. It has been shown that even when the concentration
of each compound in a mixture was below the individual toxicity effect there could be an additive effect as a mixture that was detrimental to fi shes (Schwarzenbach et al. 2006). Chemical analysis of contaminated soil and water samples usually requires sample pretreatment and extraction, which makes the inert and active portions of contaminants indistinguishable from each other, compromising the risk assessment which is concerned with the active portion (bioavailability). In contrast, BWBs assay detects contaminants’ active or bioavailable portions, and it directly links contamination to biological effects and makes the toxicity and bioavailability assessment more relevant to human health risk (Song et al. 2009; Sorensen et al. 2006). Other advantages of BWBs include 1) it is much lower cost than animal tests and eliminates the need of animals sacrifi ced for the toxicity assessment; 2) it can be quantitative (DeFraia et al. 2008), very sensitive (down to fM level), rapid, and easy to use (Massai et al. 2011; Virta et al. 1995); and 3) it requires minimal sample pretreatment and can be used for in situ or potentially online detection of pathogens and contaminants.
