Detecting Changes in the Caenorhabditis elegans Intestinal Environment Using an Engineered Bacterial Biosensor

Area of Science:

• Microbiology
• Developmental Biology
• Synthetic Biology

Background:

• The nematode *Caenorhabditis elegans* is a valuable model organism for studying host-microbe interactions due to its transparent gut and defined microbiota.
• Characterizing bacterial biosensors within a living organism is crucial for developing diagnostic tools and understanding gut environments.

Purpose of the Study:

• To develop and validate an experimental model for characterizing whole-cell bacterial biosensors *in vivo* within *Caenorhabditis elegans*.
• To demonstrate the utility of this model for detecting environmental changes in the nematode intestine.

Main Methods:

• A dual-plasmid bacterial sensor system responsive to isopropyl β-d-1-thiogalactopyranoside was engineered and characterized *in vitro*.
• The sensor's performance was evaluated *in vivo* by introducing an inducer into the *C. elegans* intestinal environment.

Main Results:

• The bacterial biosensor system was successfully developed and validated *in vitro*.
• The sensor detected and reported on specific changes within the *C. elegans* intestinal environment upon introduction of an exogenous inducer.

Conclusions:

• The developed experimental model enables *in vivo* characterization of bacterial biosensors in *C. elegans*.
• This system facilitates the rational design of engineered bacterial circuits for diagnostic applications and reduces reliance on other animal models.
• The model aids in exploring complex questions in nematode and host-microbe biology.