Whole-cell biodetection of halogenated organic acids.

A whole-cell bacterial sensor system for short-chain halo-organic acids was constructed, using 2-chloropropionic acid (2-CPA) as a model pollutant. An Escherichia coli host was transformed with a moderate-copy plasmid containing a fusion of two foreign genetic elements: (a) a promoter-containing segment of the Pseudomonas DL-DEX (DL-2-haloacid dehalogenase) encoding gene and (b) bioluminescence (luxCDABE) genes of Photorhabdus luminescens. The resulting construct, named MT1, responded to the presence of 2-CPA by dose-dependent light emission, in a highly specific albeit a very insensitive manner. Thus, while the desired concept was successfully demonstrated, further genetic work is needed in order to make such a construct practical for environmental monitoring purposes.