BDNF and depressive symptom measurement: For instance, the A. muciniphila protein Amuc_1100 (purified via recombinant expression in E. coli) has been shown to improve depression‐like behaviors in a murine model of chronic unpredictable mild stress (CUMS) by elevating serum and colonic serotonin levels, increasing brain‐derived neurotrophic factor (BDNF), and dampening neuroinflammation [94].