Bacteria Isolated From the Antarctic Sponge Iophon sp. Reveals Mechanisms of Symbiosis in Sporosarcina, Cellulophaga, and Nesterenkonia

Antarctic sponges harbor a diverse range of microorganisms that perform unique metabolic functions for nutrient cycles. Understanding how microorganisms establish functional sponge–microbe interactions in the Antarctic marine ecosystem provides clues about the success of these ancient animals in this realm. Here, we use a culture-dependent approach and genome sequencing to investigate the molecular determinants that promote a dual lifestyle in three bacterial genera Sporosarcina, Cellulophaga, and Nesterenkonia. Phylogenomic analyses showed that four sponge-associated isolates represent putative novel bacterial species within the Sporosarcina and Nesterenkonia genera and that the fifth bacterial isolate corresponds to Cellulophaga algicola. We inferred that isolated sponge-associated bacteria inhabit similarly marine sponges and also seawater. Comparative genomics revealed that these sponge-associated bacteria are enriched in symbiotic lifestyle-related genes. Specific adaptations related to the cold Antarctic environment are features of the bacterial strains isolated here. Furthermore, we showed evidence that the vitamin B5 synthesis-related gene, panE from Nesterenkonia E16_7 and E16_10, was laterally transferred within Actinobacteria members. Together, these findings indicate that the genomes of sponge-associated strains differ from other related genomes based on mechanisms that may contribute to the life in association with sponges and the extreme conditions of the Antarctic environment

Characterization of Bacterial, Archaeal and Eukaryote Symbionts from Antarctic Sponges Reveals a High Diversity at a Three-Domain Level and a Particular Signature for This Ecosystem.

Sponge-associated microbial communities include members from the three domains of life. In the case of bacteria, they are diverse, host specific and different from the surrounding seawater. However, little is known about the diversity and specificity of Eukarya and Archaea living in association with marine sponges. This knowledge gap is even greater regarding sponges from regions other than temperate and tropical environments. In Antarctica, marine sponges are abundant and important members of the benthos, structuring the Antarctic marine ecosystem. In this study, we used high throughput ribosomal gene sequencing to investigate the three-domain diversity and community composition from eight different Antarctic sponges. Taxonomic identification reveals that they belong to families Acarnidae, Chalinidae, Hymedesmiidae, Hymeniacidonidae, Leucettidae, Microcionidae, and Myxillidae. Our study indicates that there are different diversity and similarity patterns between bacterial/archaeal and eukaryote microbial symbionts from these Antarctic marine sponges, indicating inherent differences in how organisms from different domains establish symbiotic relationships. In general, when considering diversity indices and number of phyla detected, sponge-associated communities are more diverse than the planktonic communities. We conclude that three-domain microbial communities from Antarctic sponges are different from surrounding planktonic communities, expanding previous observations for Bacteria and including the Antarctic environment. Furthermore, we reveal differences in the composition of the sponge associated bacterial assemblages between Antarctic and tropical-temperate environments and the presence of a highly complex microbial eukaryote community, suggesting a particular signature for Antarctic sponges, different to that reported from other ecosystems

Summer phyto- and bacterioplankton communities during low and high productivity scenarios in the Western Antarctic Peninsula

Abstract Phytoplankton blooms taking place during the warm season drive high productivity in Antarctic coastal seawaters. Important temporal and spatial variations exist in productivity patterns, indicating local constraints influencing the phototrophic community. Surface water in Chile Bay (Greenwich Island, South Shetlands) is influenced by freshwater from the melting of sea ice and surrounding glaciers; however, it is not a widely studied system. The phyto- and bacterioplankton communities in Chile Bay were studied over two consecutive summers; during a low productivity period (chlorophyll a < 0.05 mg m−3) and an ascendant phototrophic bloom (chlorophyll a up to 2.38 mg m−3). Microbial communities were analyzed by 16S rRNA—including plastidial—gene sequencing. Diatoms (mainly Thalassiosirales) were the most abundant phytoplankton, particularly during the ascendant bloom. Bacterioplankton in the low productivity period was less diverse and dominated by a few operational taxonomic units (OTUs), related to Colwellia and Pseudoalteromonas. Alpha diversity was higher during the bloom, where several Bacteroidetes taxa absent in the low productivity period were present. Network analysis indicated that phytoplankton relative abundance was correlated with bacterioplankton phylogenetic diversity and the abundance of several bacterial taxa. Hubs—the most connected OTUs in the network—were not the most abundant OTUs and included some poorly described taxa in Antarctica, such as Neptunomonas and Ekhidna. In summary, the results of this study indicate that in Antarctic Peninsula coastal waters, such as Chile Bay, higher bacterioplankton community diversity occurs during a phototrophic bloom. This is likely a result of primary production, providing a source of fresh organic matter to bacterioplankton

Summary of the sequencing data obtained.

<p>¹ Represent high quality sequences without chimera, undesired (metazoan, chloroplast, mitochondria) and rare sequences.</p><p>Summary of the sequencing data obtained.</p

Taxonomic composition.

<p>Taxonomic distribution of assigned tag sequences of Antarctic sponge-associated and surrounding seawater (SW) microbial communities. Bars represent relative abundance of sequences belonging to given classes superior to 0.5%. (A) Bacteria/Archaea assigned with the Silva database. (B) Eukaryotes assigned with the PR2 database. <i>MyxB</i>: <i>Myxilla (Burtonanchora)</i> sp.; <i>Clat</i>: <i>Clathria</i> sp.; uDem: undetermined Demospongiae; <i>Kvar</i>: <i>Kirkpatrickia variolosa</i>; <i>Htor</i>: <i>Hymeniacidon torquata</i>; <i>Lant</i>: <i>Leucetta Antarctica</i>; <i>HalG</i>: <i>Haliclona (Gellius)</i> sp.; <i>Mann</i>: <i>Megaciella annectens</i>; SW: surrounding seawater sample.</p

Diversity measures.

<p>Non-parametric Shannon and Chao1 estimator calculated with sequences rarefied to the sample with minimum sequence number (<i>Clathria</i> sp. with 53,038 and <i>Myxilla (Burtonanchora)</i> sp. with 907 sequences for Bacteria/Archaea and Eukarya, respectively). SW: surrounding seawater sample.</p

Site and sponge species collected from different locations within Fildes Bay, King George Island, Antarctica.

<p>Site and sponge species collected from different locations within Fildes Bay, King George Island, Antarctica.</p

OTU distribution and clustering.

<p>Heatmaps representing the relative abundance (50 most abundant OTUs) of bacterial/archaeal (A) and eukaryote (B) taxa associated to Antarctic sponges and the corresponding surrounding seawater microbial communities. Their most resolved taxonomic assignation is included a side each OTU. Numbers represent taxonomic resolution level of the assignation, with (2) = Phylum, (3) = Class, (4) = Order, (5) = Family and (6) = Genus. Cluster above heatmap was generated using weighted Unifrac distance and group average clustering method. Color keys represent square root of relative abundance (in percentage). <i>MyxB</i>: <i>Myxilla (Burtonanchora)</i> sp.; <i>Clat</i>: <i>Clathria</i> sp.; uDem: undetermined Demospongiae; <i>Kvar</i>: <i>Kirkpatrickia variolosa</i>; <i>Htor</i>: <i>Hymeniacidon torquata</i>; <i>Lant</i>: <i>Leucetta Antarctica</i>; <i>HalG</i>: <i>Haliclona (Gellius)</i> sp.; <i>Mann</i>: <i>Megaciella annectens</i>; SW: surrounding seawater sample.</p

Microbial Symbionts of Antarctic Marine Benthic Invertebrates

The microbial colonization of living surfaces may be affected by several environmental and biological factors and may play an important role in the development and evolution of the holobiont. Antarctica, as an extreme and isolated environment, offers a unique opportunity to study the peculiar and often strict interactions that are established between a benthic host and its symbionts. Despite this, to date the association between microbes and Antarctic benthic invertebrates has been only seldom investigated, resulting in fragmented and poor information. This chapter will be devoted to showcase our current knowledge on prokaryotic (Bacteria and Archaea) and eukaryotic (yeasts and diatoms) microbial symbionts of Antarctic benthic invertebrate hosts, including mainly Porifera and, at to a lesser extent, Cnidaria, Echinodermata and Annelida

Erratum to: Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition) (Autophagy, 12, 1, 1-222, 10.1080/15548627.2015.1100356

non present