CORT and major depressive disorder: Four species of gut bacteria that were up-regulated by DFSF, I. valens, Ruminococcus flavefaciens, Clostridium scindens, and O. massiliensis were significantly negatively associated with adverse depression markers, including TST immobility time, plasma endotoxin, and liver ROS and MDA, hypothalamic CORT and plasma DAO.