ANTIMICROBIAL ACTIVITY IN GORGONIAN CORALS (COELENTERATA, OCTOCORALLIA)

Coral surfaces are often colonized by bacteria and other microbes that may be pathogenic as well as surface-fouling. To test the hypothesis that corals possess antimicrobial properties, both polar and non-polar extracts from eight species of gorgonian corals were assayed against five species of bacteria. Antimicrobial activity was most apparent in the non-polar fractions, which inhibited bacterial growth in all but one of the 40 interactions assayed (8 corals x 5 bacteria). Polar extracts were effective in less than 40% (14/40) of the interactions assayed. The levels of antimicrobial activity varied significantly among the gorgonian corals and was also dependent on the species of bacteria. Generally, marine bacteria were less sensitive to the extracts than were non-marine species. Differences in sclerite content among the gorgonians did not influence the levels of extract antimicrobial activity.