The Microbiome and Occurrence of Methanotrophy in Carnivorous Sponges

• Published in: Frontiers in Microbiology
• Main Authors: Hestetun, Jon T., Dahle, Håkon, Jørgensen, Steffen L., Olsen, Bernt R., Rapp, Hans T.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Zenodo 2016
• Subjects: Porifera; Cladorhizidae; Barbados; Arctic Mid-Ocean Ridge; hydrothermal vent; methane seep; isotope; Cladorhiza methanophila; European Union; Horizon 2020; Grant Agreement No 679849; Deep-sea Sponge Grounds Ecosystems of the North Atlantic an integrated approach towards their preservation and sustainable exploitation; SponGES; Arctic; Jan Mayen; North Atlantic
• Online Access: https://doi.org/10.3389/fmicb.2016.01781

As shown by recent studies, filter-feeding sponges are known to host a wide variety of microorganisms. However, the microbial community of the non-filtering carnivorous sponges (Porifera, Cladorhizidae) has been the subject of less scrutiny. Here, we present the results from a comparative study of the methanotrophic carnivorous sponge Cladorhiza methanophila from a mud volcano-rich area at the Barbados Accretionary Prism, and five carnivorous species from the Jan Mayen Vent Field (JMVF) at the Arctic Mid-Ocean Ridge. Results from 16S rRNA microbiome data indicate the presence of a diverse assemblage of associated microorganisms in carnivorous sponges mainly from the Gamma- and Alphaproteobacteria, Flavobacteriaceae, and Thaumarchaeota. While the abundance of particular groups varied throughout the dataset, we found interesting similarities to previous microbiome results from non-carnivorous deep sea sponges, suggesting that the carnivorous sponges share characteristics of a previously hypothesized putative deep-sea sponge microbial community. Chemolithoautotrophic symbiosis was confirmed for C. methanophila through a microbial community with a high abundance of Methylococcales and very light isotopic δ 13 C and δ 15 N ratios (-60 to -66‰/3.5 to 5.2‰) compared to the other cladorhizid species (-22 to -24‰/8.5 to 10.5‰). We provide evidence for the presence of putative sulfur-oxidizing Gammaproteobacteria in the arctic cladorhizids; however, δ 13 C and δ 15 N signatures did not provide evidence for significant chemoautotrophic symbiosis in this case, and the slightly higher abundance of cladorhizids at the JMVF site compared to the nearby deep sea likely stem from an increased abundance of prey rather than a more direct vent association. The phylogenetic position of C. methanophila in relation to other carnivorous sponges was established using a three-gene phylogenetic analysis, and it was found to be closely related to other non-methanotrophic Cladorhiza species with a similar morphology included in the dataset, ...