scholarly journals Anoxygenic Photosynthesis and Dark Carbon Metabolism under micro-oxic conditions in the Purple Sulfur Bacterium “Thiodictyon syntrophicum” nov. strain Cad16T

2018 ◽  
Author(s):  
Samuel M Luedin ◽  
Nicola Storelli ◽  
Francesco Danza ◽  
Samuele Roman ◽  
Matthias Wittwer ◽  
...  
Keyword(s):  
Carbon Fixation ◽  
Light Availability ◽  
Swiss Alps ◽  
Purple Sulfur Bacterium ◽  
Metabolic Functions ◽  
Pure Cultures ◽  
Dialysis Bag ◽  
Dark Carbon Fixation ◽  
Oxidative Respiration ◽  
Relative Change

1.ABSTRACTThe microbial ecosystem of the meromictic Lake Cadagno (Ticino, Swiss Alps) has been studied intensively to understand metabolic functions driven by the highly abundant anoxygenic phototrophic sulfur bacteria of the families Chromatiaceae and Chlorobiaceae. It was found that the sequenced isolate “Thiodictyon syntrophicum” nov. sp. str. Cad16T, belonging to the Chromatiaceae, may fix 26% of all bulk inorganic carbon in the chemocline at day and night. With this study, we elucidated the mode of dark carbon fixation of str. Cad16Twith a combination of long-term monitoring of key physicochemical parameters with CTD,14C-incorporation experiments and quantitative proteomics ofin situdialysis bag incubations of pure cultures. Regular vertical CTD profiling during the study period in summer 2017 revealed that the chemocline sank from 12 to 14 m which was accompanied by a bloom of cyanobacteria and the subsequent oxygenation of the deeper water column. Sampling was performed both day and night in September. While CO2assimilation rates were higher during the light period, the relative change in the proteome (663 quantified proteins) was only 1% of all CDS encoded in str. Cad16T. Oxidative respiration was thereby upregulated at light, whereas stress-related mechanisms prevailed during the night. These results indicate that the low light availability due to high cell concentrations and the oxygenation of the chemocline induced a mixotrophic growth in str. Cad16T.The complete proteome data have been deposited to the ProteomeXchange with identifier PXD010641.

scholarly journals Anoxygenic photo- and chemosynthesis of phototrophic sulfur bacteria from an alpine meromictic lake

2021 ◽  
Author(s):  
Francesco Di Nezio ◽  
Clarisse Beney ◽  
Samuele Roman ◽  
Francesco Danza ◽  
Antoine Buetti-Dinh ◽  
...  
Keyword(s):  
Carbon Fixation ◽  
Meromictic Lake ◽  
Purple Sulfur Bacterium ◽  
Phototrophic Sulfur Bacteria ◽  
Anaerobic Microorganisms ◽  
Sulfur Bacteria ◽  
Pure Cultures ◽  
Chlorobium Phaeobacteroides ◽  
Anoxic Environment ◽  
Dark Carbon Fixation

Abstract Meromictic lakes are interesting ecosystems to study anaerobic microorganisms due their permanent stratification allowing the formation of a stable anoxic environment. The crenogenic meromictic Lake Cadagno harbors an important community of anoxygenic phototrophic sulfur bacteria responsible for almost half of its total productivity. Besides their ability to fix CO2 through photosynthesis, these microorganisms also showed high rates of dark carbon fixation via chemosyntesis. Here, we grew in pure cultures three populations of anoxygenic phototrophic sulfur bacteria previously isolated from the lake, accounting for 72.8% of the total microbial community, and exibiting different phenotypes: 1) the motile, large-celled purple sulfur bacterium (PSB) Chromatium okenii, 2) the small-celled PSB Thiodictyon syntrophicum, and 3) the green sulfur bacterium (GSB) Chlorobium phaeobacteroides. We measured their ability to fix CO2 through photo- and chemo-synthesis, both in situ in the lake and in laboratory under different incubation conditions. We also evaluated the efficiency and velocity of H2S photo-oxidation, an important reaction in the anoxygenic photosynthesis process. Our results confirm that phototrophic sulfur bacteria strongly fix CO2 in the presence of light and that oxygen increases chemosynthesis at night, in laboratory conditions. Moreover, substancial differences were displayed between the three selected populations in terms of activity and abundance.

scholarly journals Microbial dark carbon fixation fueled by nitrate enrichment

2021 ◽  
Author(s):  
Joseph H. Vineis ◽  
Ashley N. Bulseco ◽  
Jennifer L. Bowen
Keyword(s):  
Microbial Communities ◽  
Marine Sediments ◽  
Salt Marshes ◽  
Carbon Fixation ◽  
Niche Partitioning ◽  
Coastal Marine Sediments ◽  
Functional Relationships ◽  
Coastal Marine ◽  
Dark Carbon Fixation ◽  
The Impact

Anthropogenic nitrate amendment to coastal marine sediments can increase rates of heterotrophic mineralization and autotrophic dark carbon fixation (DCF). DCF may be favored in sediments where organic matter is biologically unavailable, leading to a microbial community supported by chemoautotrophy. Niche partitioning among DCF communities and adaptations for nitrate metabolism in coastal marine sediments remain poorly characterized, especially within salt marshes. We used genome-resolved metagenomics, phylogenetics, and comparative genomics to characterize the potential niche space, phylogenetic relationships, and adaptations important to microbial communities within nitrate enriched sediment. We found that nitrate enrichment of sediment from discrete depths between 0-25 cm supported both heterotrophs and chemoautotrophs that use sulfur oxidizing denitrification to drive the Calvin-Benson-Bassham (CBB) or reductive TCA (rTCA) DCF pathways. Phylogenetic reconstruction indicated that the nitrate enriched community represented a small fraction of the phylogenetic diversity contained in coastal marine environmental genomes, while pangenomics revealed close evolutionary and functional relationships with DCF microbes in other oligotrophic environments. These results indicate that DCF can support coastal marine microbial communities and should be carefully considered when estimating the impact of nitrate on carbon cycling in these critical habitats.

Inorganic carbon fixation in ice-covered lakes of the McMurdo Dry Valleys

2019 ◽  
Vol 31 (3) ◽  
pp. 123-132 ◽  
Author(s):  
Trista J. Vick-Majors ◽  
John C. Priscu
Keyword(s):  
Aquatic Ecosystems ◽  
Inorganic Carbon ◽  
Carbon Fixation ◽  
Dry Valleys ◽  
Ammonia Oxidizers ◽  
Fixed Carbon ◽  
Carbon Supply ◽  
Gain Energy ◽  
Photosynthetic Microorganisms ◽  
Dark Carbon Fixation

AbstractInorganic carbon fixation, usually mediated by photosynthetic microorganisms, is considered to form the base of the food chain in aquatic ecosystems. In high-latitude lakes, lack of sunlight owing to seasonal solar radiation limits the activity of photosynthetic plankton during the polar winter, causing respiration-driven demand for carbon to exceed supply. Here, we show that inorganic carbon fixation in the dark, driven by organisms that gain energy from chemical reactions rather than sunlight (chemolithoautotrophs), provides a significant influx of fixed carbon to two permanently ice-covered lakes (Fryxell and East Bonney). Fryxell, which has higher biomass per unit volume of water, had higher rates of inorganic dark carbon fixation by chemolithoautotrophs than East Bonney (trophogenic zone average 1.0 µg C l−1 d−1vs 0.08 µg C l−1 d−1, respectively). This contribution from dark carbon fixation was partly due to the activity of ammonia oxidizers, which are present in both lakes. Despite the potential importance of new carbon input by chemolithoautotrophic activity, both lakes remain net heterotrophic, with respiratory demand for carbon exceeding supply. Dark carbon fixation increased the ratio of new carbon supply to respiratory demand from 0.16 to 0.47 in Fryxell, and from 0.14 to 0.22 in East Bonney.

scholarly journals The Genomic Capabilities of Microbial Communities Track Seasonal Variation in Environmental Conditions of Arctic Lagoons

2021 ◽  
Vol 12 ◽  
Author(s):  
Kristina D. Baker ◽  
Colleen T. E. Kellogg ◽  
James W. McClelland ◽  
Kenneth H. Dunton ◽  
Byron C. Crump
Keyword(s):  
Organic Matter ◽  
Microbial Communities ◽  
Seasonal Variability ◽  
Carbon Fixation ◽  
Light Availability ◽  
Open Water ◽  
Ice Cover ◽  
Energy Inputs ◽  
Methane Metabolism ◽  
Extreme Seasonality

In contrast to temperate systems, Arctic lagoons that span the Alaska Beaufort Sea coast face extreme seasonality. Nine months of ice cover up to ∼1.7 m thick is followed by a spring thaw that introduces an enormous pulse of freshwater, nutrients, and organic matter into these lagoons over a relatively brief 2–3 week period. Prokaryotic communities link these subsidies to lagoon food webs through nutrient uptake, heterotrophic production, and other biogeochemical processes, but little is known about how the genomic capabilities of these communities respond to seasonal variability. Replicate water samples from two lagoons and one coastal site near Kaktovik, AK were collected in April (full ice cover), June (ice break up), and August (open water) to represent winter, spring, and summer, respectively. Samples were size fractionated to distinguish free-living and particle-attached microbial communities. Multivariate analysis of metagenomes indicated that seasonal variability in gene abundances was greater than variability between size fractions and sites, and that June differed significantly from the other months. Spring (June) gene abundances reflected the high input of watershed-sourced nutrients and organic matter via spring thaw, featuring indicator genes for denitrification possibly linked to greater organic carbon availability, and genes for processing phytoplankton-derived organic matter associated with spring blooms. Summer featured fewer indicator genes, but had increased abundances of anoxygenic photosynthesis genes, possibly associated with elevated light availability. Winter (April) gene abundances suggested low energy inputs and autotrophic bacterial metabolism, featuring indicator genes for chemoautotrophic carbon fixation, methane metabolism, and nitrification. Winter indicator genes for nitrification belonged to Thaumarchaeota and Nitrosomonadales, suggesting these organisms play an important role in oxidizing ammonium during the under-ice period. This study shows that high latitude estuarine microbial assemblages shift metabolic capabilities as they change phylogenetic composition between these extreme seasons, providing evidence that these communities may be resilient to large hydrological events in a rapidly changing Arctic.

scholarly journals Dark Carbon Fixation: An Important Process in Lake Sediments

PLoS ONE ◽  
2013 ◽  
Vol 8 (6) ◽  
pp. e65813 ◽  
Author(s):  
Ana Lúcia Santoro ◽  
David Bastviken ◽  
Cristian Gudasz ◽  
Lars Tranvik ◽  
Alex Enrich-Prast
Keyword(s):  
Lake Sediments ◽  
Carbon Fixation ◽  
Important Process ◽  
Dark Carbon Fixation

scholarly journals Morphological Plasticity in a Sulfur-Oxidizing Marine Bacterium from the SUP05 Clade Enhances Dark Carbon Fixation

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Vega Shah ◽  
Xiaowei Zhao ◽  
Rachel A. Lundeen ◽  
Anitra E. Ingalls ◽  
Daniela Nicastro ◽  
...  
Keyword(s):  
Cell Size ◽  
Metabolic Activity ◽  
Carbon Fixation ◽  
Electron Tomography ◽  
Morphological Plasticity ◽  
Chemosynthetic Bacteria ◽  
Minimum Zone ◽  
Sulfur Oxidizing ◽  
Dark Carbon Fixation ◽  
Oxygen Minimum

ABSTRACT Sulfur-oxidizing bacteria from the SUP05 clade are abundant in anoxic and oxygenated marine waters that appear to lack reduced sources of sulfur for cell growth. This raises questions about how these chemosynthetic bacteria survive across oxygen and sulfur gradients and how their mode of survival impacts the environment. Here, we use growth experiments, proteomics, and cryo-electron tomography to show that a SUP05 isolate, “Candidatus Thioglobus autotrophicus,” is amorphous in shape and several times larger and stores considerably more intracellular sulfur when it respires oxygen. We also show that these cells can use diverse sources of reduced organic and inorganic sulfur at submicromolar concentrations. Enhanced cell size, carbon content, and metabolic activity of the aerobic phenotype are likely facilitated by a stabilizing surface-layer (S-layer) and an uncharacterized form of FtsZ-less cell division that supports morphological plasticity. The additional sulfur storage provides an energy source that allows cells to continue metabolic activity when exogenous sulfur sources are not available. This metabolic flexibility leads to the production of more organic carbon in the ocean than is estimated based solely on their anaerobic phenotype. IMPORTANCE Identifying shifts in microbial metabolism across redox gradients will improve efforts to model marine oxygen minimum zone (OMZ) ecosystems. Here, we show that aerobic morphology and metabolism increase cell size, sulfur storage capacity, and carbon fixation rates in “Ca. Thioglobus autotrophicus,” a chemosynthetic bacterium from the SUP05 clade that crosses oxic-anoxic boundaries.

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