Pore-forming toxins are a common type of bacterial toxins and are important bacterial virulence factors.Aerolysin is produced by Aeromonas species.It is interesting that aerolysin-like proteins are also found in vertebrates.However,the physiological roles of these proteins are still unknown.The frog species Bombina maxima lives in very harsh environments,such as pools containing microorganism-rich mud,and its skin is very "toxic.".