The role of large benthic sulfur bacteria in biogeochemical cycles - a model approach.

Mapping Intimacies ◽

10.5194/egusphere-egu21-13368 ◽

2021 ◽

Author(s):

Natalia Herran ◽

Martin Schmidt ◽

Volker Mohrholz ◽

Heide Schulz-Vogt

Keyword(s):

Sulfur Oxidation ◽

Model Framework ◽

Oxygen Minimum Zones ◽

Sulfur Bacteria ◽

Bottom Waters ◽

Conservation Efficiency ◽

Great Complexity ◽

Oxygen Minimum ◽

Model Approach

On the seabed of oxygen minimum zones (OMZ), embedded in organic-rich sediments, large sulfur bacteria (LSB) fulfil an important ecological role by detoxifying the overlying bottom waters. Thiomargarita Namibiensis and Beggiatoa spp. are chemoautotrophic microorganisms that reduce sulfur compounds to create biomass and link by doing so the carbon, sulfur, oxygen and nitrate cycle very efficiently. This particular ability make life in suboxic and hypoxic coastal waters feasible. Nevertheless, due to the complexity of sulfur oxidation and its various pathways the quantification of such activity is of great complexity. Hereby, we describe a model framework of LSB activity to implement intrinsic properties of the bacteria based on field observations and numerical modelling validations, linking the stoichiometry and energy conservation efficiency of LSB while counting for the reduced sulfur pools and its partitioning sub-products.

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A model study of warming-induced phosphorus-oxygen feedbacks in open-ocean oxygen minimum zones on millennial timescales

10.5194/esd-2016-50 ◽

2016 ◽

Author(s):

Daniela Niemeyer ◽

Tronje P. Kemena ◽

Katrin J. Meissner ◽

Andreas Oschlies

Keyword(s):

Climate Model ◽

Phosphorus Release ◽

Water Volume ◽

Low Oxygen ◽

Oxygen Minimum Zones ◽

Model Study ◽

Additional Release ◽

Bottom Waters ◽

A Minor ◽

Oxygen Minimum

Abstract. Observations indicate an expansion of oxygen minimum zones (OMZs) over the past 50 years, likely related to ongoing deoxygenation caused by reduced solubility, changes in stratification and circulation, and a potential acceleration of organic matter turnover in a warming climate. Higher temperatures also lead to enhanced weathering on land, which, in turn, increase the phosphorus and alkalinity flux into the ocean. The overall area of ocean sediments that are in direct contact with low oxygen bottom waters also increases with expanding OMZs. This leads to an additional release of phosphorus from ocean sediments and therefore raises the ocean's phosphorus inventory even further. Higher availability in phosphorus enhances biological production, remineralisation and oxygen consumption, and might therefore lead to further expansions of OMZs, representing a positive feedback. A negative feedback arises from the enhanced productivity-induced drawdown of carbon and also increased uptake of CO2 due to increased alkalinity, which, in turn, got there through weathering. This feedback leads to a decrease in atmospheric CO2 and weathering rates. Here we quantify these two competing feedbacks on millennial timescales for a high CO2 emission scenario. Using the UVic Earth System Climate Model of intermediate complexity, our model results suggest that the positive benthic phosphorus release feedback has only a minor impact on the size of OMZs in the next 1000 years, although previous studies assume that the phosphorus release feedback was the main factor for anoxic conditions during Cretaceous period. The increase in the marine phosphorus inventory under assumed business-as-usual global warming conditions originates, on millennial timescales, almost exclusively from the input via terrestrial weathering and causes a 4 to 5-fold expansion of the suboxic water volume in the model.

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Dissimilatory sulfur cycling in oxygen minimum zones: an emerging metagenomics perspective

Biochemical Society Transactions ◽

10.1042/bst20110708 ◽

2011 ◽

Vol 39 (6) ◽

pp. 1859-1863 ◽

Cited By ~ 11

Author(s):

Frank J. Stewart

Keyword(s):

Biological Diversity ◽

Marker Gene ◽

Sulfur Oxidation ◽

Sulfur Cycle ◽

Genomic Diversity ◽

Metagenomic Data ◽

Low Oxygen ◽

Carbon Cycles ◽

Oxygen Minimum Zones ◽

Oxygen Minimum

Biological diversity in marine OMZs (oxygen minimum zones) is dominated by a complex community of bacteria and archaea whose anaerobic metabolisms mediate key steps in global nitrogen and carbon cycles. Molecular and physiological studies now confirm that OMZs also support diverse micro-organisms capable of utilizing inorganic sulfur compounds for energy metabolism. The present review focuses specifically on recent metagenomic data that have helped to identify the molecular basis for autotrophic sulfur oxidation with nitrate in the OMZ water column, as well as a cryptic role for heterotrophic sulfate reduction. Interpreted alongside marker gene surveys and process rate measurements, these data suggest an active sulfur cycle with potentially substantial roles in organic carbon input and mineralization and critical links to the OMZ nitrogen cycle. Furthermore, these studies have created a framework for comparing the genomic diversity and ecology of pelagic sulfur-metabolizing communities from diverse low-oxygen regions.

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Potential role of priming effect in the open ocean oxygen minimum zones: an outlook

Hydrobiologia ◽

10.1007/s10750-021-04574-1 ◽

2021 ◽

Author(s):

P. Ragavan ◽

Sanjeev Kumar

Keyword(s):

Priming Effect ◽

Potential Role ◽

Open Ocean ◽

Oxygen Minimum Zones ◽

Oxygen Minimum

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Quantifying ecospace utilization and ecosystem engineering during the early Phanerozoic—The role of bioturbation and bioerosion

Science Advances ◽

10.1126/sciadv.abb0618 ◽

2020 ◽

Vol 6 (33) ◽

pp. eabb0618

Author(s):

Luis A. Buatois ◽

M. Gabriela Mángano ◽

Nicholas J. Minter ◽

Kai Zhou ◽

Max Wisshak ◽

...

Keyword(s):

Ecosystem Engineering ◽

Cambrian Explosion ◽

Early Cambrian ◽

Oxygen Minimum Zones ◽

Late Cambrian ◽

Stratified Ocean ◽

Marine Nearshore ◽

Oxygen Minimum ◽

Diversity Metrics

The Cambrian explosion (CE) and the great Ordovician biodiversification event (GOBE) are the two most important radiations in Paleozoic oceans. We quantify the role of bioturbation and bioerosion in ecospace utilization and ecosystem engineering using information from 1367 stratigraphic units. An increase in all diversity metrics is demonstrated for the Ediacaran-Cambrian transition, followed by a decrease in most values during the middle to late Cambrian, and by a more modest increase during the Ordovician. A marked increase in ichnodiversity and ichnodisparity of bioturbation is shown during the CE and of bioerosion during the GOBE. Innovations took place first in offshore settings and later expanded into marginal-marine, nearshore, deep-water, and carbonate environments. This study highlights the importance of the CE, despite its Ediacaran roots. Differences in infaunalization in offshore and shelf paleoenvironments favor the hypothesis of early Cambrian wedge-shaped oxygen minimum zones instead of a horizontally stratified ocean.

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Benthic phosphorus cycling in the Peruvian oxygen minimum zone

Biogeosciences Discussions ◽

10.5194/bgd-12-16755-2015 ◽

2015 ◽

Vol 12 (20) ◽

pp. 16755-16801 ◽

Cited By ~ 5

Author(s):

U. Lomnitz ◽

S. Sommer ◽

A. W. Dale ◽

C. R. Löscher ◽

A. Noffke ◽

...

Keyword(s):

Water Column ◽

Surface Sediments ◽

Solid Phase ◽

Continental Margins ◽

Low Oxygen ◽

Oxygen Minimum Zones ◽

Oxygen Conditions ◽

Bottom Waters ◽

Minimum Zone ◽

Oxygen Minimum

Abstract. Oxygen minimum zones (OMZs) that impinge on continental margins favor the release of phosphorus (P) from the sediments to the water column, enhancing primary productivity and the maintenance or expansion of low-oxygen waters. A comprehensive field program in the Peruvian OMZ was undertaken to identify the sources of benthic P, including the analysis of particles from the water column, surface sediments and pore fluids as well as in situ benthic flux measurements. A major fraction of solid phase P was bound as particulate inorganic P (PIP) both in the water column and in sediments. Sedimentary PIP increased with depth in the sediment at the expense of particulate organic P (POP). The ratio of particulate organic carbon (POC) to POP exceeded the Redfield Ratio both in the water column (202 ± 29) and in surface sediments (303 ± 77). However, the POC to total particulate P (TPP = POP + PIP) ratio was close to Redfield in the water column (103 ± 9) and in sediment samples (102 ± 15) taken from the core of the OMZ. This observation suggests that the burial efficiencies of POC and TPP are similar under the low oxygen conditions prevailing in the Peruvian OMZ. Benthic fluxes of dissolved P were extremely high (up to 1.04 ± 0.31 mmol m−2 d−1) and exceeded the fluxes resulting from the degradation of particulate organic matter raining to the seabed. Most of the excess P may have been released by bacterial mats that had stored P during previous periods when bottom waters were less reducing. At one station located at the lower rim of the OMZ, dissolved P was taken up by the sediments indicating recent phosphorite formation.

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Novel metagenome-assembled genomes involved in the nitrogen cycle from a Pacific oxygen minimum zone

ISME Communications ◽

10.1038/s43705-021-00030-2 ◽

2021 ◽

Vol 1 (1) ◽

Author(s):

Xin Sun ◽

Bess B. Ward

Keyword(s):

Nitrogen Loss ◽

Bacterial Genome ◽

Unique Role ◽

Oxygen Minimum Zones ◽

Microbial Adaptation ◽

Medium Quality ◽

Minimum Zone ◽

Oxygen Minimum ◽

Reducing Potential

AbstractOxygen minimum zones (OMZs) are unique marine regions where broad redox gradients stimulate biogeochemical cycles. Despite the important and unique role of OMZ microbes in these cycles, they are less characterized than microbes from the oxic ocean. Here we recovered 39 high- and medium-quality metagenome-assembled genomes (MAGs) from the Eastern Tropical South Pacific OMZ. More than half of these MAGs were not represented at the species level among 2631 MAGs from global marine datasets. OMZ MAGs were dominated by denitrifiers catalyzing nitrogen loss and especially MAGs with partial denitrification metabolism. A novel bacterial genome with nitrate-reducing potential could only be assigned to the phylum level. A Marine-Group II archaeon was found to be a versatile denitrifier, with the potential capability to respire multiple nitrogen compounds including N2O. The newly discovered denitrifying MAGs will improve our understanding of microbial adaptation strategies and the evolution of denitrification in the tree of life.

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Impact of tumor-parenchyma biomechanics on liver metastatic progression: a multi-model approach

Scientific Reports ◽

10.1038/s41598-020-78780-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yafei Wang ◽

Erik Brodin ◽

Kenichiro Nishii ◽

Hermann B. Frieboes ◽

Shannon M. Mumenthaler ◽

...

Keyword(s):

Time Scales ◽

Constitutive Relations ◽

Elastic Tissue ◽

Metastatic Progression ◽

Patient Death ◽

Metastatic Growth ◽

Tumor Parenchyma ◽

Short Time ◽

Model Approach

AbstractColorectal cancer and other cancers often metastasize to the liver in later stages of the disease, contributing significantly to patient death. While the biomechanical properties of the liver parenchyma (normal liver tissue) are known to affect tumor cell behavior in primary and metastatic tumors, the role of these properties in driving or inhibiting metastatic inception remains poorly understood, as are the longer-term multicellular dynamics. This study adopts a multi-model approach to study the dynamics of tumor-parenchyma biomechanical interactions during metastatic seeding and growth. We employ a detailed poroviscoelastic model of a liver lobule to study how micrometastases disrupt flow and pressure on short time scales. Results from short-time simulations in detailed single hepatic lobules motivate constitutive relations and biological hypotheses for a minimal agent-based model of metastatic growth in centimeter-scale tissue over months-long time scales. After a parameter space investigation, we find that the balance of basic tumor-parenchyma biomechanical interactions on shorter time scales (adhesion, repulsion, and elastic tissue deformation over minutes) and longer time scales (plastic tissue relaxation over hours) can explain a broad range of behaviors of micrometastases, without the need for complex molecular-scale signaling. These interactions may arrest the growth of micrometastases in a dormant state and prevent newly arriving cancer cells from establishing successful metastatic foci. Moreover, the simulations indicate ways in which dormant tumors could “reawaken” after changes in parenchymal tissue mechanical properties, as may arise during aging or following acute liver illness or injury. We conclude that the proposed modeling approach yields insight into the role of tumor-parenchyma biomechanics in promoting liver metastatic growth, and advances the longer term goal of identifying conditions to clinically arrest and reverse the course of late-stage cancer.

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Sulfur bacteria promote dissolution of authigenic carbonates at marine methane seeps

The ISME Journal ◽

10.1038/s41396-021-00903-3 ◽

2021 ◽

Author(s):

Dalton J. Leprich ◽

Beverly E. Flood ◽

Peter R. Schroedl ◽

Elizabeth Ricci ◽

Jeffery J. Marlow ◽

...

Keyword(s):

Carbonate Rocks ◽

Sulfur Oxidation ◽

Methane Seeps ◽

Etch Pits ◽

Active Dissolution ◽

Authigenic Carbonates ◽

Sulfur Bacteria ◽

Sulfur Oxidizing ◽

Sulfur Oxidizing Bacteria

AbstractCarbonate rocks at marine methane seeps are commonly colonized by sulfur-oxidizing bacteria that co-occur with etch pits that suggest active dissolution. We show that sulfur-oxidizing bacteria are abundant on the surface of an exemplar seep carbonate collected from Del Mar East Methane Seep Field, USA. We then used bioreactors containing aragonite mineral coupons that simulate certain seep conditions to investigate plausible in situ rates of carbonate dissolution associated with sulfur-oxidizing bacteria. Bioreactors inoculated with a sulfur-oxidizing bacterial strain, Celeribacter baekdonensis LH4, growing on aragonite coupons induced dissolution rates in sulfidic, heterotrophic, and abiotic conditions of 1773.97 (±324.35), 152.81 (±123.27), and 272.99 (±249.96) μmol CaCO3 • cm−2 • yr−1, respectively. Steep gradients in pH were also measured within carbonate-attached biofilms using pH-sensitive fluorophores. Together, these results show that the production of acidic microenvironments in biofilms of sulfur-oxidizing bacteria are capable of dissolving carbonate rocks, even under well-buffered marine conditions. Our results support the hypothesis that authigenic carbonate rock dissolution driven by lithotrophic sulfur-oxidation constitutes a previously unknown carbon flux from the rock reservoir to the ocean and atmosphere.

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