Bringing microbial diversity into focus: high‐resolution analysis of iron mats from the Lō‘ihi Seamount

Abstract

Thirty kilometers south of the island of Hawai'i lies the Lō'ihi Seamount, an active submarine volcano that hosts a network of low-temperature hydrothermal vents enriched in ferrous iron that supports extensive microbial mats. These mats, which can be a half a meter deep, are composed of ferric iron bound to organic polymers - the metabolic byproduct of iron-oxidizing Zetaproteobacteria. Though the role of Zetaproteobacteria in mat formation is well established, we have a limited understanding of how differences in diversity are related to mat morphology. We used Minimum Entropy Decomposition and ZetaOtu classification to demonstrate cryptic diversity between closely related Zetaproteobacteria while showing habitat and geographic specificity. Veiled mats, common structures at Lō'ihi, exhibit distinct community composition and contain diversity not detected in other mat types, including specific Zetaproteobacteria and an unclassified Gammaproteobacteria. Our analyses also indicate that diversity can change dramatically across small spatial transects from points of active venting, yet we found comparatively few differences between major sampling sites. This study provides a better picture of the microbiome responsible for iron mat production at Lō'ihi and has broad implications for our understanding of these globally distributed communities.

Validating the Cyc2 neutrophilic Fe oxidation pathway using meta-omics of Zetaproteobacteria iron mats at marine hydrothermal vents

“…Many samples were dominated by the Zetaproteobacteria, notably sample S1 (96% Zetaproteobacteria), a cm-scale sample of actively growing Fe mat surface. In addition to Zetaproteobacteria, the mats hosted variable flanking microbial communities that differed between the three sites ( Supplemental Figure 3 ; Supplemental Figure 4 ), but were similar to previous studies [9, 22, 23, 57, 58]. Overall, the relatively simple, Zetaproteobacteria-rich composition of these marine Fe mats makes them good systems for studying neutrophilic Fe oxidation mechanisms.…”

Bacterial Community on a Guyot in the Northwest Pacific Ocean Influenced by Physical Dynamics and Environmental Variables

“…They play an important role in deep-ocean biogeochemical processes and potentially contribute to high productivity in the deep ocean (McNichol et al, 2018). Microorganisms have been extensively studied in different environments of marine subseafloor, especially in extreme environments (e.g., hydrothermal vent and cold seep), where they are active and diverse in physiology and metabolism, contributing significantly to energy flow in deep ocean (Fullerton et al, 2017;Huber et al, 2007;López-García et al, 2003;Meyers et al, 2014;Moyer et al, 1995;Scott et al, 2017;Sogin et al, 2006;Teske et al, 2002).…”

In situestimates of iron-oxidation and accretion rates for iron-oxidizing bacterial mats at Lō’ihi Seamount

“…We speculate that the period chamber 6 was not in vent flow may vents that are the hottest fluids currently observed at Lō'ihi. This suggests that as the 442 vents have cooled Zetaproteobacteria have become more prevalent, and is consistent with 443 detectable sulfide being largely absent from the vent fluids in 2013 (Scott et al, 2016.). 444…”

“…• The community membership that grew during short-term incubations reflected the 47 community composition of nearby microbial mats. 48 49 50 51 often referred to as hydrous ferric oxides (HFO) in part because they are poorly 97 crystalline oxides, composed primarily of ferrihydrite, with large surface areas that 98 adsorb water and are relatively buoyant (Emerson, 2016). These biogenic oxides undergo 99 diagenesis to crystalline forms more slowly than synthesized iron oxides, probably as a 100 result of containing organic ligands, as well as becoming silicified (Kennedy et al, 2004; their production is important to understanding their contribution as a global iron source.…”

“…These 362 veil-like mats form farther from vent fluid sources (e.g. in cooler regions with more O 2 363 and less Fe(II) compared to mats where stalks and Y's predominate(Scott et al, 2016). 364The cells that produce the Y-structures are easily detached during sampling (Chan 365 et al, 2016), and the freshly produced Y-type structures that were plentiful in the 366 cassettes had few apical cells associated with them.…”