Salicylate-induced, lux gene dependent bioluminescence was measured using a cooled charge-coupled device (CCD) camera to evaluate its potential as a quantitative measurement of cell density of Pseudomonas fluorescens HK44 in porous media. The CCD camera was able to detect bioluminescence from cell densities between 1x10⁶ and 1x10⁸ cells/ml in both...