The main ambition of Psycho_Metabo project is to help deliver effective and safe adjunct therapy for depression. Depression treatment is an uphill battle due to low efficiency and serious side effects of antidepressants. Gut microbiota-based treatments emerged as a promising ally; however, mechanisms of action still wait to be discovered. Novel GABA-producing bacterial strain Phocaeicola vulgatus NGB218, isolated and characterized during our previous study (NextGenBiotics, SFRS, IDEAS), ameliorated depression-like behavior in rats subjected to chronic unpredictable mild stress (CUMS) – most commonly used animal model of depression. Psycho_Metabo aims to characterize the psychobiotic potential of P. vulgatus NGB218 on molecular level by investigating its effects on the metabolome of cerebrospinal fluid (CSF). CSF metabolom will be analysed using Nuclear Magnetic Resonance (NMR) spectroscopy. The aim is to detect changes in content and concentration of CSF metabolites in CUMS model, and to investigate whether P. vulgatus NGB218 may prevent or ameliorate those changes. The results will also add to the literature on CSF metabolites involved in gut microbiota-host cross-talk within microbiota-gut-brain axis.