Detection of Human Fecal Metabolites Using a Bacterial Biosensor

Begin with a bacterial biosensor culture suspended in a medium.

These engineered bacteria produce a transcription factor that, upon binding to a specific fecal metabolite, activates a promoter associated with a fluorescent reporter gene.

To this culture, add a filtered human fecal sample containing metabolites, such as lactate, that are involved in host-microbiome interactions.

Dilute this mixture with a fresh medium to maintain an optimal reaction volume.

Incubate without shaking to mimic the human gut environment.

The fecal metabolites diffuse into the bacterial cell and bind to the transcription factor.

This complex binds to the promoter and leads to reporter gene expression and protein production.

Mix the solution for uniform distribution, dilute it in a buffer, and analyze it using flow cytometry.

As the bacterial cells pass through a laser, fluorescence emitted by the reporter proteins confirms the presence of the specific fecal metabolite.