Harvard researchers have found that M. morganii may contribute to depression by producing an inflammatory molecule.

• Biochemical analyses reveal how the gut bacterium Morganella morganii may contribute to some cases of major depressive disorder.
• The bacterium incorporates an environmental contaminant into one of its molecules, triggering inflammation — a known factor in disease development.
• These findings suggest the contaminant could serve as a biomarker and further support the idea that major depressive disorder may have autoimmune connections.