Psychobiotics as a novel strategy for alleviating anxiety and depression

[Display omitted] •Discuss the potential gut microbiota biomarker in the progress of depression.•Summarize the methods for rapid identification of psychobiotics.•Comprehensively reveal the ways in which probiotics exert its antidepressant effects.•Perspect the market potential of psychobiotics and the problems need to be solved. Anxiety and depression have become major health challenges in recent decades. Accumulating evidence suggests that gut microbial dysbiosis may have a profound effect on the pathogenesis of mood disorders. As an important ‘microbial organ’, the gut microbiota directly participates in nutrient metabolism and peripheral immune regulation and even distantly affects brain functions and behaviours. This review provides an overview of recent discoveries regarding how the gut microbiota influences anxiety and depression and aims to establish the key signalling pathways between the gut microbiota and the brain. Finally, the psychobiotic strategy for treating mood disorders is discussed, covering both pre-clinical and clinical studies. Psychobiotic treatment could provide a novel therapeutic approach to treat anxiety and depression.