The antibacterial activity of the hemichordate Saccoglossus ruber (Enteropneusta)

Antibacterial activity of crude whole body homogenates and mucus from the body surface of the hemichordate Saccoglossus ruber was detected using a turbidometric and plate assay. Activity was found to be strongest against marine bacteria and significantly higher against bacteria isolated from the immediate environment of the animals. The whole body nomogenate was less effective at inhibiting growth of the seven terrestrial bacteria tested. The antibacterial factor from the homogenate retained its activity after boiling and was stable at room temperature for at least 8 weeks, suggesting that it was nonproteinaceous. The loss of all activity during dialysis also indicated that a low molecular weight substance was involved. The antibacterial factor from the mucus and homogenate had similar properties, so that the same molecule may have been involved. The possibility that the antibacterial factor may be related to the halogenated indoles and phenols occurring in other enteropneusts is discussed.