Simultaneous detection of analytes based on genetically engineered whole cell sensing systems

Sensing systems for the simultaneous detection of analytes utilizing whole cells provide efficient ways to develop analytical assay systems with reduc ed cost. In this work, a whole cell-based sensing system was developed for the simultaneous detection of two model analytes, beta -lactose and L-arabi nose, using genetically-designed bacteria. Two variants of the green fluore scent protein (GFP), BFP2 and GFPuv, were used as the reporter protein for the detection of each analyte. The corresponding reporter genes were introd uced into the bacteria in such a way that they can be co-expressed along wi th the other genes induced by the respective sugar. Each of these fluoresce nt proteins is expressed only in the presence of their respective analyte a nd their fluorescence emission can be monitored using the intact whole cell samples. By exciting the cells at 380 nm, emission for BFP2 and GFPuv can be collected at 440 and 509 run, respectively. The fluorescence emission th us obtained can be correlated with the amount of sugars present in the samp le. Calibration curves for beta -lactose and L-arabinose were generated. It was observed that this system shows no significant response to other close ly related sugars thus providing high selectivity for beta -lactose and L-a rabinose detection. (C) 2001 Elsevier Science BN. All rights reserved.