Sposensor: A Whole-Bacterial Biosensor That Uses Immobilized <i>Bacillus subtilis</i> Spores and a One-Step Incubation/Detection Process

A generic whole-cell bacterial sensor called sposensor was developed with immobilized sporesfrom engineered <i>Bacillus subtilis</i>. Sposensor contains two different types of spores: reporting spores that contain a reporter gene fused to a promoter responding to a compound to be detected, and control spores use to monitor cell germination and viability. A one-step incubation/detection process was developed to meet the constraints of on-site analysis. Spores were directly incubated with culture medium containing the compound to be detected. β-Galactosidase was chosen as a reporter protein in both cases and its activity followed by a colorimetric assay. Results showed that sposensor was efficient in detecting two different compounds, a metal (Zn²⁺) and a peptidic antibiotic (bacitracin). Owing to the stability and robustness of spores, sposensor is a very efficient and easy tool to manipulate for analyzing the presence of toxic compounds in natural settings.