Biology subjects

McGonigle, J. M.

Publications and source records attributed to McGonigle, J. M..

4 recordsLinked to original sources

bioRxiv2022

Metabolic strategies shared by basement residents of the Lost City hydrothermal field

Alkaline fluids venting from chimneys of the Lost City hydrothermal field flow from a potentially vast microbial habitat within the seafloor where energy and organic molecules are released by chemical reactions within rocks uplifted from Earths mantle. In this study, we investigated hydrothermal fluids venting from Lost City chimneys as windows into subseafloor environments where the products of geochemical reactions, such as hydrogen (H2), formate, and methane, may be the only available sources of energy for biological activity. Our deep sequencing of metagenomes and metatranscriptomes from these hydrothermal fluids revealed a few key species of archaea and bacteria that are likely to play critical roles in the subseafloor microbial ecosystem. We identified a population of Thermodesulfovibrionales (belonging to phylum Nitrospirae) as a prevalent sulfate-reducing bacterium that may be responsible for much of the consumption of H2 and sulfate in Lost City fluids. Metagenome-assembled genomes (MAGs) classified as Methanosarcinaceae and Candidatus Bipolaricaulota were also recovered from venting fluids and represent potential methanogenic and acetogenic members of the subseafloor ecosystem. These genomes share novel hydrogenases and formate dehydrogenase-like sequences that may be unique to hydrothermal and subsurface alkaline environments where hydrogen and formate are much more abundant than carbon dioxide. The results of this study include multiple examples of metabolic strategies that appear to be advantageous in hydrothermal and subsurface environments where energy and carbon are provided by geochemical reactions. IMPORTANCEThe Lost City hydrothermal field is an iconic example of a microbial ecosystem fueled by energy and carbon from Earths mantle. Uplift of mantle rocks into the seafloor can trigger a process known as serpentinization that releases hydrogen and creates unusual environmental conditions where simple organic carbon molecules are more stable than dissolved inorganic carbon. This study provides an initial glimpse into the kinds of microbes that live deep within the seafloor where serpentinization takes place, by sampling hydrothermal fluids exiting from the Lost City chimneys. The metabolic strategies that these microbes appear to be using are also shared by microbes that inhabit other sites of serpentinization, including continental subsurface environments and natural springs. Therefore, the results of this study contribute to a broader, interdisciplinary effort to understand the general principles and mechanisms by which serpentinization-associated processes can support life on Earth and perhaps other worlds.

microbiology↗

bioRxiv2021

Metabolic Potential of Microbial Communities in the Hypersaline Sediments of the Bonneville Salt Flats

The Bonneville Salt Flats (BSF) appear to be entirely desolate when viewed from above, but in reality they host rich microbial communities just below the surface salt crust. In this study, we investigate the metabolic potential of the BSF microbial ecosystem. The predicted and measured metabolic activities provide new insights into the ecosystem functions of evaporite landscapes and are an important analog for potential subsurface microbial ecosystems on ancient and modern Mars. Hypersaline and evaporite systems have been investigated previously as astrobiological analogs for Mars and other salty celestial bodies. Still, these studies have generally focused on aquatic systems and cultivation-dependent approaches. Here, we present an ecosystem-level examination of metabolic pathways within the shallow subsurface of evaporites. We detected aerobic and anaerobic respiration as well as methanogenesis in BSF sediments. Metagenome-assembled genomes (MAGs) of diverse bacteria and archaea encoded a remarkable diversity of metabolic pathways, including those associated with carbon fixation, carbon monoxide oxidation, acetogenesis, methanogenesis, sulfide oxidation, denitrification, and nitrogen fixation. These results demonstrate the potential for multiple energy sources and metabolic pathways in BSF and highlight the possibility for vibrant microbial ecosystems in the shallow subsurface of evaporites.

microbiology↗

bioRxiv2019

Genomic Evidence for Formate Metabolism by Chloroflexi as the Key to Unlocking Deep Carbon in Lost City Microbial Ecosystems

The Lost City hydrothermal field on the Mid-Atlantic Ridge supports dense microbial life on the lofty calcium carbonate chimney structures. The vent field is fueled by chemical reactions between the ultramafic rock under the chimneys and ambient seawater. These serpentinization reactions provide reducing power (as hydrogen gas) and organic compounds that can serve as microbial food; the most abundant of these are methane and formate. Previous studies have characterized the interior of the chimneys as a single-species biofilm inhabited by the Lost City Methanosarcinales, but also indicated that this methanogen is unable to metabolize formate. The new metagenomic results presented here indicate that carbon cycling in these Lost City chimney biofilms could depend on the metabolism of formate by low-abundance Chloroflexi species. Additionally, we present evidence that metabolically diverse, formate-utilizing Sulfurovum species are living in the transition zone between the interior and exterior of the chimneys.\n\nIMPORTANCEPrimitive forms of life may have originated around hydrothermal vents at the bottom of the ancient ocean. The Lost City hydrothermal vent field, fueled by just rock and water, provides an analog for not only primitive ecosystems but also extraterrestrial ecosystems that might support life. The microscopic life covering towering chimney structures at the Lost City has been well characterized, yet little is known about the carbon cycling in this ecosystem. These results provide a better understanding of how carbon from the deep subsurface can fuel rich microbial ecosystems on the seafloor.

microbiology↗

bioRxiv2019

Robust archaeal and bacterial communities inhabit shallow subsurface sediments of the Bonneville Salt Flats

We report the first census of natural microbial communities of the Bonneville Salt Flats (BSF), a perennial salt pan at the Utah-Nevada border. Environmental DNA sequencing of archaeal and bacterial 16S rRNA genes was conducted on samples from multiple evaporite sediment layers of the surface salt crust. Our results show that at the time of sampling (September 2016), BSF hosted a robust microbial community dominated by diverse Halobacteriaceae and Salinibacter species. Desulfuromonadales from GR-WP33-58 are also abundant in all samples. We identified taxonomic groups enriched in each layer of the salt crust sediment and revealed that the upper gypsum sediment layer found immediately under the uppermost surface halite contains a robust microbial community. We found an increased presence of Thermoplasmatales, Nanohaloarchaeota, Woesearchaeota, Acetothermia, Halanaerobium, Parcubacteria, Planctomycetes, Clostridia, Gemmatimonadetes, Marinilabiaceae and other Bacteroidetes in this upper gypsum layer. This study provides insight into the diversity, spatial heterogeneity, and geologic context of a surprisingly complex microbial ecosystem within this macroscopically-sterile landscape. IMPORTANCEOver the last [~]13,000 years the Pleistocene Lake Bonneville, which covered a large portion of Utah, drained and desiccated leaving behind the Bonneville Salt Flats (BSF). Today BSF is famous for its use as a speedway, which has hosted many land-speed records and a community that greatly values this salty landscape. Additionally, the salts that saturate BSF basin are extracted and sold as an additive for agricultural fertilizers. The salt crust is a well-known recreational and economic commodity, but the roles of microbes in the formation and maintenance of the salt crust are generally unknown. This study is the first geospatial analysis of microbial diversity at this site using cultivation-independent environmental DNA sequencing methods. Identification of the microbes present within this unique, dynamic, and valued sedimentary evaporite environment is an important step toward understanding the potential consequences of perturbations to the microbial ecology on the surrounding landscape and ecosystem.

microbiology↗