BACTERIA-BASED CHEMILUMINESCENCE SENSING SYSTEM USING BETA-GALACTOSIDASE UNDER THE CONTROL OF THE ARSR REGULATORY PROTEIN OF THE ARS OPERON

A highly sensitive and selective sensing system for antimonite and ars enite was developed based on genetically engineered bacteria harboring the plasmid pBGD23. In this plasmid, arsR, the gene encoding for the ArsR regulatory protein of the ars operon, is fused to lacZ, the gene encoding for the reporter enzyme beta-galactosidase. The expression of beta-galactosidase in E. coli strains bearing pBGD23 is controlled by ArsR, and this can be related to the concentration of antimonite/arse nite employed to induce the production of beta-galactosidase in the ba cteria. ArsR has a high specificity for antimonite/arsenite, thus conf erring the developed sensing system with high selectivity. This was de monstrated by evaluating several oxoanions and soft metals as potentia l interferents. The concentration of beta-galactosidase expressed in t he bacteria was monitored by chemiluminescence. Using this sensing sys tem, antimonite can be detected at concentrations as low as 10(-15) M. The importance of the E. coli chromosomal ars operon on the observed response was evaluated by employing a strain of E. coli where the chro mosomal ars operon has been deleted. (C) 1998 Elsevier Science B.V. Al l rights reserved.