Gut inflammation often requires monitoring through invasive and costly procedures, creating a need for noninvasive diagnostic methods. This project focuses on designing a bacterial biosensor that detects intestinal inflammation by sensing tetrathionate, a biomarker produced during inflammatory responses in the gut. The biosensor uses the tetrathionate response promoter PttrB, regulated by the TtrS/TtrR two-component system identified in Salmonella. The membrane-bound sensor kinase TtrS detects tetrathionate and activates the response regulator TtrR through phosphorylation. Activated TtrR binds to the PttrB promoter and initiates transcription of a downstream reporter gene. The reporter gene lacZ was selected because it produces the enzyme β-galactosidase and functions without oxygen, making it suitable for anaerobic gut conditions. When lacZ is expressed in the presence of X-gal, bacterial colonies turn blue, providing a visible indicator that tetrathionate has been detected. This color change confirms detection of the inflammation marker. This project demonstrates the conceptual design of a gut-compatible bacterial biosensor capable of sensing an inflammation-associated biomarker and producing a measurable response. Such systems could support future development of noninvasive diagnostic or therapeutic engineered bacteria for monitoring and managing intestinal inflammation.