Dataset Information

Microbial Diversity and Connectivity in Deep-Sea Sediments of the South Atlantic Polar Front.

ABSTRACT: Ultraslow spreading ridges account for one-third of the global mid-ocean ridges. Their impact on the diversity and connectivity of benthic deep-sea microbial assemblages is poorly understood, especially for hydrothermally inactive, magma-starved ridges. We investigated bacterial and archaeal diversity in sediments collected from an amagmatic segment (10°-17°E) of the Southwest Indian Ridge (SWIR) and in the adjacent northern and southern abyssal zones of similar water depths within one biogeochemical province of the Indian Ocean. Microbial diversity was determined by 16S ribosomal RNA (rRNA) gene sequencing. Our results show significant differences in microbial communities between stations outside and inside the SWIR, which were mostly explained by environmental selection. Community similarity correlated significantly with differences in chlorophyll a content and with the presence of upward porewater fluxes carrying reduced compounds (e.g., ammonia and sulfide), suggesting that trophic resource availability is a main driver for changes in microbial community composition. At the stations in the SWIR axial valley (3,655-4,448 m water depth), microbial communities were enriched in bacterial and archaeal taxa common in organic matter-rich subsurface sediments (e.g., SEEP-SRB1, Dehalococcoida, Atribacteria, and Woesearchaeota) and chemosynthetic environments (mainly Helicobacteraceae). The abyssal stations outside the SWIR communities (3,760-4,869 m water depth) were dominated by OM1 clade, JTB255, Planctomycetaceae, and Rhodospirillaceae. We conclude that ultraslow spreading ridges create a unique environmental setting in sedimented segments without distinct hydrothermal activity, and play an important role in shaping microbial communities and promoting diversity, but also in connectivity among deep-sea habitats.

SUBMITTER: Varliero G

PROVIDER: S-EPMC6465420 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Publications

Microbial Diversity and Connectivity in Deep-Sea Sediments of the South Atlantic Polar Front.

Varliero Gilda G Bienhold Christina C Schmid Florian F Boetius Antje A Molari Massimiliano M

Frontiers in microbiology 20190409

Ultraslow spreading ridges account for one-third of the global mid-ocean ridges. Their impact on the diversity and connectivity of benthic deep-sea microbial assemblages is poorly understood, especially for hydrothermally inactive, magma-starved ridges. We investigated bacterial and archaeal diversity in sediments collected from an amagmatic segment (10°-17°E) of the Southwest Indian Ridge (SWIR) and in the adjacent northern and southern abyssal zones of similar water depths within one biogeoche ...[more]

PMID: 31024475

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Project description:Metagenomics of marine sediments has uncovered a broad diversity of new uncultured taxa and provided insights into their metabolic capabilities. Here, we detected microbial lineages from a sediment core near the Jiulong methane reef of the northern South China Sea (at 1,100-m depth). Assembly and binning of the metagenomes resulted in 11 genomes (>85% complete) that represented nine distinct phyla, including candidate phyla TA06 and LCP-89, Lokiarchaeota, Heimdallarchaeota, and a newly described globally distributed phylum (B38). The genome of LCP-89 has pathways for nitrate, selenate, and sulfate reduction, suggesting that they may be involved in mediating these important processes. B38 are able to participate in the cycling of hydrogen and selenocompounds. Many of these uncultured microbes may also be capable of autotrophic CO2 fixation, as exemplified by identification of the Wood-Ljungdahl (W-L) pathway. Genes encoding carbohydrate degradation, W-L pathway, Rnf-dependent energy conservation, and Ni/Fe hydrogenases were detected in the transcriptomes of these novel members. Characterization of these new lineages provides insight to the undescribed branches in the tree of life.IMPORTANCE Sedimentary microorganisms in the South China Sea (SCS) remain largely unknown due to the complexity of sediment communities impacted by continent rifting and extension. Distinct geochemical environments may breed special microbial communities including microbes that are still enigmatic. Functional inference of their metabolisms and transcriptional activity provides insight in the ecological roles and substrate-based interactivity of these uncultured Archaea and Bacteria These microorganisms play different roles in utilizing inorganic carbon and scavenging diverse organic compounds involved in the deep-sea carbon cycle. The genomes recovered here contributed undescribed species to the tree of life and laid the foundation for future study on these novel phyla persisting in marginal sediments of the SCS.

Dataset Information

Microbial Diversity and Connectivity in Deep-Sea Sediments of the South Atlantic Polar Front.

Publications

Microbial Diversity and Connectivity in Deep-Sea Sediments of the South Atlantic Polar Front.

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