Host Species Determines Symbiotic Community Composition in Antarctic Sponges (Porifera: Demospongiae)

Oriol Sacristán-Soriano,Natalia Pérez Criado,Conxita Avila

doi:10.3389/fmars.2020.00474

Abstract

The microbiota of four Antarctic sponges, Dendrilla antarctica, Sphaerotylus antarcticus, Mycale acerata, and Hemigellius pilosus, collected at two South Shetland Islands and at two locations in the Antarctic Peninsula separated by ca. 670 km, were analyzed together with surrounding seawater. We used high throughput sequencing of the V4 region of the 16S rRNA gene common to Bacteria and Archaea to investigate the microbial diversity and community composition. Our study reveals that sponge-associated prokaryote communities are consistently detected within a particular sponge species regardless of the collection site. Their community structure and composition are typical of low microbial abundance (LMA) sponges. We conclude that prokaryote communities from Antarctic sponges are less diverse and differ in their composition compared to those in the water column. Microbiome analysis indicates that Antarctic sponges harbor a strict core consisting of seven OTUs, and a small variable community comprising several tens of OTUs. Two abundant prokaryotes from the variable microbiota that are affiliated to the archaeal and bacterial phyla Thaumarchaeota and Nitrospirae may be involved in the sponge nitrification process and might be relevant components of the nitrogen cycling in Antarctica. The likely generalist nature of dominant microbes and the host-specific structure of symbiont communities suggest that these Antarctic sponges represent different ecological niches for particular microbial enrichments.

Highlights

Sponges are sessile organisms widely distributed from the tropics to the poles (Hooper and Van Soest, 2004), and ecologically important constituents of benthic environments from shallow to deep waters (Bell, 2008)
Twenty-eight bacterial and three archaeal phyla were detected in the 11,187 operational taxonomic units (OTUs) recovered from seawater and sponge samples, which were predominantly affiliated to the phyla Proteobacteria and Bacteroidetes (Supplementary Figure S2)
4,619 OTUs were recovered from D. antarctica, 3,438 OTUs from S. antarcticus, 1,381 OTUs from M. acerata, and 1,490 OTUs from H. pilosus

Summary

Introduction

Sponges (phylum Porifera) are sessile organisms widely distributed from the tropics to the poles (Hooper and Van Soest, 2004), and ecologically important constituents of benthic environments from shallow to deep waters (Bell, 2008). Despite the continuous flux of seawater through their canal system, sponges are able to maintain a specific microbial composition remarkably different from the ambient seawater (Thomas et al, 2016; Hill and Sacristán-Soriano, 2017). These associations appear to be host-specific and stable under different environmental conditions (Hentschel et al, 2002; Lee et al, 2011; Erwin et al, 2012b; Schmitt et al, 2012; Pita et al, 2013; Reveillaud et al, 2014). Sponge-microbial interactions seem to be consistent over geographic regions, there are some apparent geographical gaps in the study of host-associated prokaryotic assemblages

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Results

Conclusion