Fiber optic detection of in situ lux reporter gene activity in porous media: system design and performance

A luminescence detection system is described that couples a genetically eng ineered bioluminescent reporter organism and fiber optic technology for mon itoring in situ reporter gene activity in porous media under dynamic condit ions. The reporter bacterium used was Pseudomonas putida RB1353, which carr ies plasmids NAH7 and pUTK9 that encode genes for salicylate degradation (n ah) and luminescence (lux) that are regulated by the same promoter. The sys tem can be used to examine the relationship between microbial activity and the resultant impact on biodegradation and transport of salicylate in porou s media. Several batch and column experiments were conducted to analyze the performance of the fiber optic detection system. Batch studies showed that the fiber optic response in liquid cultures was linearly correlated to a c alibrated system response using a liquid scintillation counter in the singl e photon counting mode. In column studies, it was demonstrated that decreas es in salicylate and dissolved oxygen concentrations associated with biodeg radation were correlated with an increase in luminescence response. The max imum luminescence given off by the reporter organism was linearly related t o salicylate concentration. These results indicate that the fiber optic sys tem can be used to monitor microbial activity under dynamic conditions. Thi s system allows rapid, real-time, and non-destructive measurements of lumin escence from a specific lux reporter microbial population in porous media. (C) 2000 Elsevier Science B.V. All rights reserved.