FIBER-OPTIC-BASED BIOMONITORING OF BENZENE-DERIVATIVES BY RECOMBINANTESCHERICHIA-COLI BEARING LUCIFERASE GENE-FUSED TOL-PLASMID IMMOBILIZED ON THE FIBER OPTIC END

TOL plasmid in Pseudomonas putida mt-2 has a series of genes for the d egradation of xylene, toluene, and their derivatives to pyruvate and a cetaldehyde (or propionaldehyde), Two operons, i.e., upper operon and meta operon, play indispensable roles for the digestion of xylene deri vatives: When XylR protein recognizes xylene derivatives, another cont rolling gene, xylS, is activated, which results in the activation of m eta operon, Therefore, we have constructed a fusion gene between TOL p lasmid and the firefly luciferase gene under the control of XylR and t he promoter of xylS gene; i.e., by using fusions of the meta operon wi th promotorless luciferase expression vector from firefly, we have con structed and tested biomonitors for benzene derivatives, Bioluminescen ce specified by Escherichia coli (pTSN316), carrying xylR and xylS pro moters, Amp(r), and luc, was measured in either a benzene derivative-s aturated or o-methylbenzyl alcohol-dissolved medium both in the case o f cell suspension and in the case of immobilized cell form, The utilit y of the biosensing system for monitoring in chemical plant drainage w as demonstrated with samples supplemented with benzene derivatives, Th e xylR-xylS promoter-lux fusion carried by pTSN316 responded to a benz ene-related chemical in sample solutions. Immobilization of the transf ormed E. coli, at one end of fiber optic, bearing firefly luciferase g ene fused to TOL plasmid, has been demonstrated to fabricate a lumines cent remote biomonitoring device for the protection of environmental d eterioration, Due to the luminescent detection, the detection limits f or benzene-related aromatics that are recognized by a binding protein (XylR) were parts-per-million, We had already submitted a preliminary report concerning the possibility of environmental monitoring based on the above idea by using the transformed E. coli in a cell-suspended s olution, This paper describes mainly a fiber-optic-based biomonitoring device for the protection of environmental deterioration.