ABSTRACT
A number of echinoderms produce bioactive secondary metabolites. The function of these compounds remains uncertain, but they may provide defense from predation, fouling, and/or infection. In order to examine whether bioactive compounds are present, and can potentially deter microbial growth, ethanolic body-wall extracts of 22 species of echinoderms (1 crinoid, 3 holothuroids, 3 ophiuroids, and 15 asteroids) from the northern Gulf of Mexico were tested for antimicrobial activity against 19 marine and non-marine microorganisms. A disc diffusion assay was employed to measure the ability of extracts to inhibit microbial growth. Eighty percent of the extracts tested inhibited the growth of at least one or more microbes. Body-wall extracts from fourteen species of echinoderms inhibited growth of Gram (+), non-marine bacteria, and accounted for the highest incidence of antimicrobial activity. Ten body-wall extracts inhibited growth of Gram (−), non-marine bacteria; four inhibited Gram (−) marine bacteria. Extracts of the asteroids Henricia downeyae and Chaetaster nodosa displayed antifungal activity against Sordaria fimicola. The asteroid Goniaster tesselatus displayed a broad spectrum of activity inhibiting Gram (+) and Gram (−) non-marine bacteria, and Gram (−) marine bacteria. The absence of antimicrobial activity in most echinoderm extracts exposed to marine bacteria indicates that these compounds extracted from echinoderms may serve functions other than solely the inhibition of microbial growth.
