An optical detection module-based biosensor using fortified bacterial beads for soil toxicity assessment

An optical biosensor module for soil contamination assessment is presented, employing bioluminescent bacterial bioreporters encapsulated in poly-dopamine (PD)-coated alginate microbeads. The PD-coated beads displayed improved mechanical strength and stability, but somewhat delayed responses to the inducing toxicant. Using toluene as a model soil contaminant, two bioluminescent reporter strains were employed for its detection in the ambient light-blocking, temperature-controlled biosensor module. Bioluminescence of strain TV1061 (harboring an inducible grpE::luxCDABE fusion) increased and that of strain GC2 (harboring a constitutive lac::luxCDABE fusion) decreased in the presence of increasing toluene concentrations. In the former case, a maximal effect was observed in the presence of 1% toluene. This simple optical detection biosensor module may potentially be utilized for monitoring soil contamination from areas suspected of chemical pollution such petrochemical industrial zones or petrol stations.