The incidence of antibacterial activity in marine demospongiae; systematic and geographic considerations

Thirty species of temperate-zone sponges representative of all orders of the Demospongiae have been tested for antibacterial activity. The results indicate the following: that a higher percentage of temperate than tropical species produced active extracts (87% as opposed to 58%); that sponge extracts more frequently inhibited the growth of marine bacteria than they did non-marine bacteria (76.5% compared to 56%); that 46.5% of the extracts tested inhibited growth of Gram-negative bacteria while only 6.5% inhibited growth of Gram-positive bacteria. There is no obvious correlation between incidence of antibacterial activity and latitude of occurrence, systematic group or growth form of the sponge. It is suggested that antibacterial agents produced by sponges may have a role in enhancing the efficiency with which sponges retain bacterial food.