Comparative Study of Guaymas Basin Microbiomes: Cold Seeps vs. Hydrothermal Vents Sediments

Abstract

In the Guaymas Basin, the presence at a few tens of kilometers of cold seeps and hydrothermal vents coupled with comparable sedimentary settings and depths offer a unique opportunity to assess and compare the microbial community composition of these deep-sea ecosystems. The microbial diversity in sediments from three cold seep and two hydrothermal vent assemblages were investigated using high-throughput 16S rRNA-sequencing. Numerous bacterial and archaeal lineages were detected in both cold seep and hydrothermal vent sediments. Various potential organic matter degraders (e.g., Chloroflexi, Atribacteria, MBG-D) and methane and sulfur cycling related microorganisms (e.g., ANME and methanogenic lineages, sulfate-reducing lineages) were detected in both ecosystems. This suggests that analogous metabolic processes such as organic matter degradation and anaerobic methane oxidation coupled to sulfate reduction, were probably occurring in these two contrasted ecosystems. These highlighted "core microbiome" of the Guaymas Basin chemosynthetic ecosystems might therefore result from the combined presence of up-rising fluid emissions and high sedimentary rates of organic matter in the Basin. These results, coupled with the detailed ribotype analysis of major archaeal lineages (ANME-1, ANME-2, and MBG-D), also suggest a potential connectivity among deep-sea ecosystems of the Guaymas Basin likely due to the sedimentary context and the absence of physical border. However, thermophilic and hyperthermophilic lineages (e.g., Thermodesulfobacteria, Desulfurococcales, etc.) were exclusively identified in hydrothermally impacted sediments highlighting the strong influence of temperature gradients and other hydrothermally-related factors such as thermogenic sulfate reduction and sulfide formation on microbial community composition.

The Guaymas Basin Subseafloor Sedimentary Archaeome Reflects Complex Environmental Histories

“…Comparison with other Sonora Margin cores highlights the seep characteristics of core SeepP06. Based on the presence or absence of major archaeal lineages, SeepP06 archaeal communities are similar to surficial (<1 mbsf) communities from Sonora Margin cold seeps, predominantly comprising Thermoplasmata (MBG-D), Bathyarchaea, and ANME lineages ( Cruaud et al., 2017 ). The SeepP06 archaeal communities share dominant archaeal lineages—the Thermoplasmatales (MBG-D), Lokiarchaeota, and Bathyarchaeota—with Sonora Margin subsurface sediments (core BCK1 [ Vigneron et al., 2014 ]).…”

“…Numerous seep sites with carbonate outcrops and cold seep fauna have been observed on an eroding pressure ridge that follows the transform fault at the base of the Sonora Margin ( Simoneit et al., 1990 ; Paull et al., 2007 ); the seep communities at these sites are largely based on methanotrophy and sulfide oxidation ( Portail et al., 2015 ). Seep communities and sulfide-oxidizing microbial mats are also widespread on the Sonora Margin slopes ( Vigneron et al., 2014 ; Cruaud et al., 2017 ).…”

Artificial construction of the biocoenosis of deep‐sea ecosystem via seeping methane

“…In deep‐sea cold seeps, hydrocarbons (such as gas hydrate or petroleum), reduced gases (hydrogen sulfide) and carbon dioxide emerge from the seafloor (Sen et al ., 2018). The signature of deep‐sea hydrothermal vents is richness in hydrogen sulfide, carbon monoxide, methane and hydrogen gases, which erupt from these vents (Cruaud et al ., 2017). The most abundant component of the gases emitted from cold seeps is methane (Sen et al ., 2018), while hydrogen sulfide accounts for the greatest proportion of the gases emitted from hydrothermal vents (Cruaud et al ., 2017).…”

“…The signature of deep‐sea hydrothermal vents is richness in hydrogen sulfide, carbon monoxide, methane and hydrogen gases, which erupt from these vents (Cruaud et al ., 2017). The most abundant component of the gases emitted from cold seeps is methane (Sen et al ., 2018), while hydrogen sulfide accounts for the greatest proportion of the gases emitted from hydrothermal vents (Cruaud et al ., 2017). Both methane and hydrogen sulfide are reduced gases, in which the central element (carbon or sulfur) is in its lowest valence state, and thus, it can easily lose electrons (Martin et al ., 2008; Nunoura et al ., 2012).…”

The Guaymas Basin Subseafloor Sedimentary Archaeome Reflects Complex Environmental Histories

“…Numerous seep sites with carbonate 74 outcrops and cold seep fauna have been observed on an eroding pressure ridge that follows the 75 transform fault at the base of the Sonora Margin (Simoneit et al, 1990;Paull et al, 2007); the 76 seep communities at these sites are largely based on methanotrophy and sulfide oxidation 77 (Portail et al, 2015). Seep communities and sulfide-oxidizing microbial mats are also 78 widespread on the Sonora Margin slopes (Vigneron et al, 2014;Cruaud et al, 2017). 79…”