Effects of Caribbean sponge secondary metabolites on bacterial surface colonization

Abstract

Crude organic tissue extracts from 8 species of Caribbean sponges were assayed for inhibitory effects on surface colonization using 24 environmental marine bacterial isolates, 4 known marine invertebrate pathogens, and 1 common fouling bacterium. Each extract was tested for its effects on bacterial attachment, growth and swarming. The 24 bacterial strains were isolated from sponge surfaces, nearby substrata, or adjacent seawater. Extracts were incorporated into agar for assays of bacterial attachment and swarming. Growth-inhibition assays were conducted with the standard agar disk-diffusion assay. Of the 24 bacterial isolates, 23 were significantly inhibited from attaching to an extract-treated agar surface; 1 isolate from the surface of Agelas conifera exhibited significantly enhanced attachment on agar treated with the extract of that sponge. Sponge extracts had the least effect on growth: of 184 assays, 11 displayed significant antibacterial activity, all of these from 4 sponge species (A. conifera, Ailochroia crassa, Amphimedon compressa, and Aplysina fulva). The same isolate from the surface of A. conifera that exhibited enhanced attachment in response to the extract of that sponge exhibited inhibited growth in response to the same extract. Six out of 24 bacterial isolates exhibited swarming, the majority (67%) of which were isolated from substratum sources. Extracts from 4 of the 8 sponge species (the same species as listed above) inhibited swarming in all 6 strains, while the remaining extracts enhanced, inhibited, or had no effect on swarming depending on the strain. Bioassay-guided fractionation of the extract of A. crassa yielded 2 compounds responsible for inhibiting attachment and swarming, respectively. Ianthellin was identified as the metabolite that inhibited attachment, whereas another brominated tryosine metabolite inhibited swarming. Chemical defenses of sponges may target microbial attachment, and to a lesser degree influence swarming and growth. Non-toxic metabolites may play the greatest role in affecting bacterial epibiosis on the surfaces of marine sponges.

Sponge-Associated Microorganisms: Evolution, Ecology, and Biotechnological Potential

“…It is highly likely that sponges produce metabolites which allow them to disrupt AHL-regulated phenotypes, as shown for the macroalga Delisea pulchra (126,127,223,224) and various terrestrial plants (302,393). Indeed, inhibition of bacterial swarming by chemical extracts from sponges has recently been shown, though it has yet to be clarified whether this is an AHL-specific effect (184). Associations between sponges and microorganisms can be maintained over different generations in either of the following two ways: (i) microbes can be recruited from the surrounding water by filter feeding (i.e., horizontal or environmental transmission) or (ii) microbial symbionts can be passed on from the parent sponge via reproductive stages (i.e., vertical transmission) (Fig.…”

Chemical warfare on coral reefs: Sponge metabolites differentially affect coral symbiosis in situ

“…Among Caribbean reef sponges, clear patterns are emerging of chemical defenses against predators, competitors, and pathogens (Pawlik 1997;Engel and Pawlik 2005;Kelly et al 2005). With the present work, sponge allelopathy can be added to the list of important biotic determinants of coral cover, which include recruitment, predation by fish and invertebrates, and competition with macroalgae, and this further underscores the complexity of coral reef ecosystem function.…”

“…1a), and coral tissues exposed to this treatment were also the most visibly bleached. This sponge contains pyrrole-imidazole alkaloids, including the metabolite oroidin, already known as potent antipredatory and antimicrobial defenses (Chanas et al 1996;Kelly et al 2005) that may also play a role in sponge-coral allelopathy. Most of the sponge metabolite treatments exhibited impaired photosynthesis with little or no effect on bleaching.…”

Antiparasitic bromotyrosine derivatives from the Caribbean marine sponge Aiolochroia crassa

“…7 A wide range of biological activities have been reported for these compounds including antimicrobial, enzymatic, cytotoxic and antiparasitic activities. 8 A previous study on the sponge A. crassa led to the discovery of antimicrobial activity of its extracts, 9 and the isolation and identification of several bromotyrosine derivatives, namely:…”