Two distinct microbial communities revealed in the sponge Cinachyrella

This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by the Frontiers Research Foundation. The published article can be found at: http://www.frontiersin.org/Microbiology.Marine sponges are vital components of benthic and coral reef ecosystems, providing\ud shelter and nutrition for many organisms. In addition, sponges act as an essential carbon\ud and nutrient link between the pelagic and benthic environment by filtering large quantities\ud of seawater. Many sponge species harbor a diverse microbial community (including\ud Archaea, Bacteria and Eukaryotes), which can constitute up to 50% of the sponge\ud biomass. Sponges of the genus Cinachyrella are common in Caribbean and Floridian\ud reefs and their archaeal and bacterial microbiomes were explored here using 16S rRNA\ud gene tag pyrosequencing. Cinachyrella specimens and seawater samples were collected\ud from the same South Florida reef at two different times of year. In total, 639 OTUs\ud (12 archaeal and 627 bacterial) belonging to 2 archaeal and 21 bacterial phyla were\ud detected in the sponges. Based on their microbiomes, the six sponge samples formed\ud two distinct groups, namely sponge group 1 (SG1) with lower diversity (Shannon-Wiener\ud index: 3.73 ± 0.22) and SG2 with higher diversity (Shannon-Wiener index: 5.95 ± 0.25). Hosts’ 28S rRNA gene sequences further confirmed that the sponge specimens\ud were composed of two taxa closely related to Cinachyrella kuekenthalli. Both sponge\ud groups were dominated by Proteobacteria, but Alphaproteobacteria were significantly\ud more abundant in SG1. SG2 harbored many bacterial phyla (>1% of sequences) present\ud in low abundance or below detection limits (