Selectivity of whole cell optical biosensor with immobilized bioreporter Pseudomonas fluorescens HK44

Pseudomonas fluorescens HK44, a whole-cell bacterial bioreporter that responds to naphthalene and salicylate exposure by production of visible light, was immobilized to thick (1 mm) silica films prepared from pre-polymerized tetramethoxysilane. Bioluminescence was first detected 50 min after induction; maximum was reached after 4.5 h and followed saturation dependence on the inducer concentration. Higher cell concentration resulted in higher bioluminescence and in lower mechanical stability. Minimal concentration inducing detectable bioluminescence was 1.2 and 0.5 mg/l for naphthalene and salicylate, respectively. From 32 possible inducers of bioluminescence (11 substituted naphthalenes, 7 substituted salicylic acids, 6 o-substituted benzoic acids, 7 substituted phenols) only salicylaldehyde, 2-aminobenzoic acid, 4-methylsalicylic acid and 4-chlorosalicylic acid induced bioluminescence, however the minimal inducing concentration was two to three orders of magnitude higher compared to salicylate.