In this study, we show the repetitive detection of toluene on a tapered optical fiber element (OFE) with an attached layer of Pseudomonas putida TVA8 bioluminescent bioreporters. The bioluminescent cell layer was attached on polished quartz modified with (3-aminopropyl)triethoxysilane (APTES). The repeatability of the preparation of the optical probe and its use was demonstrated with five differently shaped OFEs. The intensity of measured bioluminescence was minimally influenced by the OFE shape, possessing transmittances between 1.41% and 5.00%. OFE probes layered with P. putida TVA8 were used to monitor liquid toluene over a two-week period. It was demonstrated that OFE probes layered with positively induced P. putida TVA8 bioreporters were reliable detectors of toluene. A toluene concentration of 26.5 mg/L was detected after <30 min after immersion of the probe in the toluene solution. Additional experiments also immobilized constitutively bioluminescent cells of E. coli 652T7, on OFEs with polyethyleneimine (PEI). These OFEs were repetitively induced with Lauria-Bertani (LB) nutrient medium. Bioluminescence appeared 15 minutes after immersion of the OFE in LB. A change in pH from 7 to 6 resulted in a decrease in bioluminescence that was not restored following additional nutrient inductions at pH 7. The E. coli 652T7 OFE probe was therefore sensitive to negative influences but could not be repetitively used.

A whole-cell optical fiber sensor of toluene was prepared by the adsorption of Pseudomonas putida TVA8, the bacterial strain producing light in contact with toluene, in the form of biofilm. Bioreporter immobilization was facilitated by (3-Aminopropyl)triethoxysilane (APTES) treatment on the wider end of tapered quartz optical fiber element (OFE). Repeatability of preparation and response of the active part of the biosensor was demonstrated in five trials with different OFE geometries in which the bioluminescence (BL) was induced with toluene solution (26.5 mg L ⁻¹ ) for 2 weeks. Longevity of inductions of the biosensor was shown in over 135 days trial, when the biosensor was repetitively induced with toluene solution (26.5 mg L ⁻¹ ) 68 times. The intensities of BL gradually decreased due to release of the adsorbed cells and they were only temporarily restored by the addition of nutrients. The intensities of BL induced with contaminated ground water were lower than in the mineral medium (MSM) with the same content of toluene. Ideal shape of OFE, which maximizes the detected signal, was calculated to be a Frustrum cone. The developed sensor is plausible for multiple and fast online monitoring of the presence of a pollutant in remote localities but not its concentration.