Coral high molecular weight carbohydrates support opportunistic microbes in bacterioplankton from an algae-dominated reef
Thobor, B.M.; Haas, A.F.; Wild, C.; Nelson, C.E.; Wegley Kelly, L.; Hehemann, J.-H.; Arts, M.G.I.; Boer, M.; Buck-Wiese, H.; Nguyen, N.P.; Hellige, I.; Mueller, B. (2024). Coral high molecular weight carbohydrates support opportunistic microbes in bacterioplankton from an algae-dominated reef. mSystems 9(11): e00832-24. https://dx.doi.org/10.1128/msystems.00832-24
In: mSystems. American Society for Microbiology: Washington, DC. e-ISSN 2379-5077, more
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| Author keywords |
coral-algae phase shift; carbohydrates; 16S rRNA sequencing; microbial metabolism; microbialization; opportunism |
| Authors | | Top |
- Thobor, B.M.
- Haas, A.F., more
- Wild, C.
- Nelson, C.E.
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- Wegley Kelly, L.
- Hehemann, J.-H.
- Arts, M.G.I., more
- Boer, M.
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- Buck-Wiese, H.
- Nguyen, N.P.
- Hellige, I.
- Mueller, B.
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| Abstract |
High molecular weight (HMW; >1 kDa) carbohydrates are a major component of dissolved organic matter (DOM) released by benthic primary producers. Despite shifts from coral to algae dominance on many reefs, little is known about the effects of exuded carbohydrates on bacterioplankton communities in reef waters. We compared the monosaccharide composition of HMW carbohydrates exuded by hard corals and brown macroalgae and investigated the response of the bacterioplankton community of an algae-dominated Caribbean reef to the respective HMW fractions. HMW coral exudates were compositionally distinct from the ambient, algae-dominated reef waters and similar to coral mucus (high in arabinose). They further selected for opportunistic bacterioplankton taxa commonly associated with coral stress (i.e., Rhodobacteraceae, Phycisphaeraceae, Vibrionaceae, and Flavobacteriales) and significantly increased the predicted energy-, amino acid-, and carbohydrate-metabolism by 28%, 44%, and 111%, respectively. In contrast, HMW carbohydrates exuded by algae were similar to those in algae tissue extracts and reef water (high in fucose) and did not significantly alter the composition and predicted metabolism of the bacterioplankton community. These results confirm earlier findings of coral exudates supporting efficient trophic transfer, while algae exudates may have stimulated microbial respiration instead of biomass production, thereby supporting the microbialization of reefs. In contrast to previous studies, HMW coral and not algal exudates selected for opportunistic microbes, suggesting that a shift in the prevalent DOM composition and not the exudate type (i.e., coral vs algae) per se, may induce the rise of opportunistic microbial taxa. |
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