Biogeochemical Cycling Paper Suggestion

Coral-Associated Bacteria and Their Role in the Biogeochemical Cycling of Sulfur

Raina, J.B., Tapiolas, D., Willis, B.L., & D.G. Bourne. 2009. Coral-Associated Bacteria and Their Role in the Biogeochemical Cycling of Sulfur. Appl. Env. Microbiology  vol. 75;11. pp3492-3501. doi:  10.1128/AEM.02567-08

Marine bacteria play a central role in the degradation of dimethylsulfoniopropionate (DMSP) to dimethyl sulfide (DMS) and acrylic acid, DMS being critical to cloud formation and thereby cooling effects on the climate. High concentrations of DMSP and DMS have been reported in scleractinian coral tissues although, to date, there have been no investigations into the influence of these organic sulfur compounds on coral-associated bacteria. Two coral species,  Montipora aequituberculata  and  Acropora millepora, were sampled and their bacterial communities were characterized by both culture-dependent and molecular techniques. Four genera,  Roseobacter, Spongiobacter, Vibrio, and  Alteromonas, which were isolated on media with either DMSP or DMS as the sole carbon source, comprised the majority of clones retrieved from coral mucus and tissue 16S rRNA gene clone libraries. Clones affiliated with  Roseobacter  sp. constituted 28% of the  M. aequituberculata  tissue libraries, while 59% of the clones from the  A. millepora  libraries were affiliated with sequences related to the  Spongiobacter  genus.  Vibrio  spp. were commonly isolated from DMS and acrylic acid enrichments and were also present in 16S rRNA gene libraries from coral mucus, suggesting that under “normal’ environmental conditions, they are a natural component of coral-associated communities. Genes homologous to  dddD, and  dddL, previously implicated in DMSP degradation, were also characterized from isolated strains, confirming that bacteria associated with corals have the potential to metabolize this sulfur compound when present in coral tissues. Our results demonstrate that DMSP, DMS, and acrylic acid potentially act as nutrient sources for coral-associated bacteria and that these sulfur compounds are likely to play a role in structuring bacterial communities in corals, with important consequences for the health of both corals and coral reef ecosystems.

 

I chose this article because of the diversity of microbial analysis methods used in the paper: 16S rRNA amplicon sequencing, traditional culturing, and functional gene amplicon sequencing. In addition, Im very interested in the implications of coral-associated DMS producing bacteria and their affect on climate change, especially given the recent bleaching and mass die off events in teh Great Barrier Reef.

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