Taxonomic diversity of microbial communities in sub-seafloor hydrothermal sediments of the active Santorini-Kolumbo volcanic field

Paraskevi N Polymenakou; Paraskevi Nomikou; Mark Hannington; Sven Petersen; Stephanos P Kilias; Thekla I Anastasiou; Vasiliki Papadimitriou; Eleutheria Zaka; Jon Bent Kristoffersen; Danai Lampridou; Sandra Wind; Verena Heinath; Sabine Lange; Antonios Magoulas

doi:10.3389/fmicb.2023.1188544

Taxonomic diversity of microbial communities in sub-seafloor hydrothermal sediments of the active Santorini-Kolumbo volcanic field

Front Microbiol. 2023 Jun 29:14:1188544. doi: 10.3389/fmicb.2023.1188544. eCollection 2023.

Authors

Affiliations

¹ Hellenic Centre for Marine Research, Institute of Marine Biology, Biotechnology, and Aquaculture, Heraklion, Greece.
² Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens, Athens, Greece.
³ GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
⁴ Department of Biology, University of Crete, Heraklion, Greece.
⁵ Department of Earth and Environmental Sciences, University of Ottawa, Ottawa, ON, Canada.
⁶ Institute of Geosciences, University of Kiel (CAU), Kiel, Germany.

Abstract

Introduction: Active hydrothermal vents of volcanic origin provide a remarkable manifestation of life on Earth under extreme conditions, which may have consequences for our understanding of habitability on other terrestrial bodies as well.

Methods: Here, we performed for the first time Illumina sequencing of bacterial and archaeal communities on sub-seafloor samples collected from the Santorini-Kolumbo volcanic field. A total of 19 (3-m long) gravity corers were collected and processed for microbial community analysis.

Results: From a total of 6,46,671 produced V4 sequences for all samples, a total of 10,496 different Operational Taxonomic Units (OTUs) were identified that were assigned to 40 bacterial and 9 archaeal phyla and 14 candidate divisions. On average, the most abundant phyla in all samples were Chloroflexi (Chloroflexota) (24.62%), followed by Proteobacteria (Pseudomonadota) (11.29%), Firmicutes (Bacillota) (10.73%), Crenarchaeota (Thermoproteota) (8.55%), and Acidobacteria (Acidobacteriota) (8.07%). At the genus level, a total of 286 known genera and candidate genera were mostly dominated by members of Bacillus, Thermoflexus, Desulfatiglans, Pseudoalteromonas, and Pseudomonas.

Discussion: In most of the stations, the Chao1 values at the deeper layers were comparable to the surface sediment samples denoting the high diversity in the subsurface of these ecosystems. Heatmap analysis based on the 100 most abundant OTUs, grouped the sampling stations according to their geographical location, placing together the two hottest stations (up to 99°C). This result indicates that this specific area within the active Kolumbo crater create a distinct niche, where microorganisms with adaptation strategies to withstand heat stresses can thrive, such as the endospore-forming Firmicutes.

Keywords: Kolumbo volcano; Santorini (Greece); diversity; hydrothermal vent field; microbial community composition and diversity; submarine volcano.

Grants and funding

This study was supported by the project “SANTORini’s seafloor volcanic observatorY” (SANTORY) [Hellenic Foundation for Research and Innovation (HFRI) Grant Number 185], by the project THIRA (funded by Municipality of Thira), by the project “New catalytic enzymes and enzymatic processes from the marine microbiome for refining marine seaweed biomass” (MARIKAT) (European Union’s Horizon 2020 research and innovation programme under Grant Agreement 817992), by the project “Centre for the study and sustainable exploitation of Marine Biological Resources (CMBR)” (MIS 5002670), and the project “Managing and Analyzing Life Sciences Data (ELIXIR-GR)” (MIS 5002780). This research was supported in part through computational resources provided by the IMBBC (Institute of Marine Biology, Biotechnology and Aquaculture) of the HCMR. Funding for establishing the IMBBC HPC has been received by the MARBIGEN (EU Regpot) project, LifeWatchGreece RI and the CMBR (Centre for the study and sustainable exploitation of Marine Biological Resources) RI. Sampling was performed within the framework of the POSEIDON POS510 Expedition of GEOMAR-Helmholtz Centre for Ocean Research Kiel that took place from 06.03.2017-29.03.2017 in the Mediterranean Sea−Aegean Sea with the RV Poseidon.