Lactobacillus delbrueckii reduces anxiety in zebrafish through gut microbiome

Certain bacteria possess the ability to reduce anxiety- and stress-related behaviorsthrough the gut microbiome-brain axis. Such bacteria are called psychobiotics, and can be used to improve mood and cognition. However, only a few bacteria have been characterized as psychobiotics, and their exact mechanism of action remains unclear. Hence, in this study we analyzed three different Lactobacillus species, namely, L. paracasei , L. delbrueckii , and L. casei , for their potential psychobiotic activities. L. delbrueckii treatment reduced anxiety-like behavior and increased brain and gut glutamic acid decarboxylase ( gad ) gene expression in zebrafish