Energy landscapes shape microbial communities in hydrothermal systems on the Arctic Mid-Ocean Ridge

Abstract

Methods developed in geochemical modelling combined with recent advances in molecular microbial ecology provide new opportunities to explore how microbial communities are shaped by their chemical surroundings. Here, we present a framework for analyses of how chemical energy availability shape chemotrophic microbial communities in hydrothermal systems through an investigation of two geochemically different basalt-hosted hydrothermal systems on the Arctic Mid-Ocean Ridge: the Soria Moria Vent field (SMVF) and the Loki's Castle Vent Field (LCVF). Chemical energy landscapes were evaluated through modelling of the Gibbs energy from selected redox reactions under different mixing ratios between seawater and hydrothermal fluids. Our models indicate that the sediment-influenced LCVF has a much higher potential for both anaerobic and aerobic methane oxidation, as well as aerobic ammonium and hydrogen oxidation, than the SMVF. The modelled energy landscapes were used to develop microbial community composition models, which were compared with community compositions in environmental samples inside or on the exterior of hydrothermal chimneys, as assessed by pyrosequencing of partial 16S rRNA genes. We show that modelled microbial communities based solely on thermodynamic considerations can have a high predictive power and provide a framework for analyses of the link between energy availability and microbial community composition.

The Microbiome and Occurrence of Methanotrophy in Carnivorous Sponges

“…Gammaproteobacteria in groups related to known sulfur-oxidizing bacteria were prominent in the microbiome across different cladorhizids in this study. Hydrogen sulfide is present in high concentrations in the high-temperature fluids venting from white smokers at the Troll Wall site at the JMVF (Baumberger, 2011; Dahle et al, 2015). However, sulfur oxidation, which seems to be a common feature in deep-sea sponges, may, if indeed it signifies chemolithoautotrophy, account for a smaller portion of the nutrient uptake than the methanotrophic symbiosis in C. methanophila .…”

Relative Importance of Chemoautotrophy for Primary Production in a Light Exposed Marine Shallow Hydrothermal System

“…Chemoautotrophic microorganisms in hydrothermal systems are able to assimilate inorganic carbon into biomass and effectively transfer the energy from the geothermal source to higher trophic levels (e.g., Sievert and Vetriani, 2012). The general knowledge of chemoautotrophy at deep-sea hydrothermal vents has advanced considerably over the last years (e.g., Flores et al, 2011; Hügler and Sievert, 2011; Dahle et al, 2015; Stokke et al, 2015; Fortunato and Huber, 2016; McNichol et al, 2016). However, hydrothermal systems can harbor heterogeneous microbial habitats (e.g., Santelli et al, 2008; Flores et al, 2011; Olins et al, 2013; Reeves et al, 2014; Stokke et al, 2015) and it is often difficult to obtain samples or to perform in situ measurements at deep-sea vents (e.g., Sievert and Vetriani, 2012; Reeves et al, 2014; McNichol et al, 2016).…”

Abyssivirga alkaniphila gen. nov., sp. nov., an alkane-degrading, anaerobic bacterium from a deep-sea hydrothermal vent system, and emended descriptions of Natranaerovirga pectinivora and Natranaerovirga hydrolytica

“…A biofilm (10ROV9BS) was sampled in 2010 from a black smoker wall at the LCVF (738 339 N 88 099 E, depth 2349 m below sea level) using a 1 l hydraulic cylinder (biosyringe) as described previously (Dahle et al, 2015). Sample material was transferred to 50 ml anaerobic culture bottles with Met II growth medium amended with crude oil immediately upon arrival at the surface.…”