Abstract
Most pathogens in intestine are opportunist, called "opportunistic pathogens" that usually do not cause disease in a healthy host. Only when the host's resistance is lowered or the intestinal microecological balance is destroyed, the opportunistic pathogens are capable of causing disease. Here, two opportunistic pathogens, Salmonella enteritidis and Vibrio parahaemolyticus were chosen to test the possible antagonistic effect of the probiotic agent Clostridium butyricum on these pathogens infections in vitro using fish intestinal epithelial cells (FIECs). The C. butyricum and its spent culture supernatants exhibited significant inhibitory activity on S. enteritidis and V. parahaemolyticus growth and adherence to FIECs. The C. butyricum also showed significant inhibitory effects on S. enteritidis and V. parahaemolyticus induced apoptosis, which may due to its growth and adhesion inhibitory effects. These results indicated that the probiotic bacterium C. butyricum has preventive and therapeutic effects on S. enteritidis and V. parahaemolyticus infections in fish.