scholarly journals Hydrogen-based metabolism – an ancestral trait in lineages sibling to the Cyanobacteria

2018 ◽  
Author(s):  
Paula B. Matheus Carnevali ◽  
Frederik Schulz ◽  
Cindy J. Castelle ◽  
Rose Kantor ◽  
Patrick Shih ◽  
...  
Keyword(s):  
Electron Acceptor ◽  
Anaerobic Respiration ◽  
Fine Tuning ◽  
Oxygenic Photosynthesis ◽  
Aerobic Respiration ◽  
Terminal Electron Acceptor ◽  
Anoxic Conditions ◽  
Transport Chain ◽  
Candidate Division ◽  
Ocean Ecosystem

AbstractThe metabolic machinery from which microbial aerobic respiration evolved is tightly linked to the origins of oxygenic Cyanobacteria (Oxyphotobacteria). Even though the majority of Oxyphotobacteria are photoautotrophs and can use carbohydrates with oxygen (O2) as the electron acceptor, all are fermenters under dark anoxic conditions. Studies suggest that the ancestor of Oxyphotobacteria may have used hydrogen (H2) as an electron donor and that two types of NiFe hydrogenases are essential for its oxidation. Melainabacteria and Sericytochromatia, close phylogenetic neighbors to Oxyphotobacteria comprise fermentative and aerobic representatives, or organisms capable of both. Margulisbacteria (candidate divisions RBX-1 and ZB3) and Saganbacteria (candidate division WOR-1), a novel cluster of bacteria phylogenetically related to Melainabacteria, Sericytochromatia and Oxyphotobacteria may further constrain the metabolic platform in which oxygenic photosynthesis and aerobic respiration arose. Here, we predict the metabolisms of Margulisbacteria and Saganbacteria from new and published metagenome-assembled genomes (MAGs) and single amplified genomes (SAGs), and compare them to their phylogenetic neighbors. Sediment-associated Margulisbacteria are predicted to have a fermentation-based metabolism featuring a variety of hydrogenases, a nitrogenase for nitrogen (N2) fixation, and electron bifurcating complexes involved in cycling of ferredoxin and NAD(P)H. Overall, the genomic features suggest the capacity for metabolic fine-tuning under strictly anoxic conditions. In contrast, the genomes of Margulisbacteria from the ocean ecosystem encode an electron transport chain that supports aerobic growth. Similarly, some Saganbacteria genomes encode various hydrogenases, and others may have the ability to use O2 under certain conditions via a putative novel type of heme copper O2 reductase. Like Melainabacteria and Sericytochromatia, Margulisbacteria and Saganbacteria have diverse energy metabolisms capable of fermentation, and aerobic or anaerobic respiration. In summary, our findings support the hypothesis that the ancestor of these groups was an anaerobe in which fermentation and H2 metabolism were central metabolic features. Our genomic data also suggests that contemporary lineages sibling to the Oxyphotobacteria may have acquired the ability to use O2 as a terminal electron acceptor under certain environmental conditions.

scholarly journals Geobacter sulfurreducens Can Grow with Oxygen as a Terminal Electron Acceptor

2004 ◽  
Vol 70 (4) ◽  
pp. 2525-2528 ◽  
Author(s):  
W. C. Lin ◽  
M. V. Coppi ◽  
D. R. Lovley
Keyword(s):  
Electron Acceptor ◽  
Atmospheric Oxygen ◽  
Geobacter Sulfurreducens ◽  
Terminal Electron Acceptor ◽  
Anoxic Conditions ◽  
Strict Anaerobe ◽  
Subsurface Environments

ABSTRACT Geobacter sulfurreducens, previously classified as a strict anaerobe, tolerated exposure to atmospheric oxygen for at least 24 h and grew with oxygen as the sole electron acceptor at concentrations of 10% or less in the headspace. These results help explain how Geobacter species may survive in oxic subsurface environments, being poised to rapidly take advantage of the development of anoxic conditions.

scholarly journals Respiration and Growth of Shewanella decolorationis S12 with an Azo Compound as the Sole Electron Acceptor

2006 ◽  
Vol 73 (1) ◽  
pp. 64-72 ◽  
Author(s):  
Yiguo Hong ◽  
Meiying Xu ◽  
Jun Guo ◽  
Zhicheng Xu ◽  
Xingjuan Chen ◽  
...  
Keyword(s):  
Electron Transport ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Azo Dyes ◽  
Anaerobic Respiration ◽  
Defined Medium ◽  
Whole Cells ◽  
Azo Compound ◽  
Transport Chain ◽  
Dissimilatory Azoreduction

ABSTRACT The ability of Shewanella decolorationis S12 to obtain energy for growth by coupling the oxidation of various electron donors to dissimilatory azoreduction was investigated. This microorganism can reduce a variety of azo dyes by use of formate, lactate, pyruvate, or H2 as the electron donor. Furthermore, strain S12 grew to a maximal density of 3.0 × 107 cells per ml after compete reduction of 2.0 mM amaranth in a defined medium. This was accompanied by a stoichiometric consumption of 4.0 mM formate over time when amaranth and formate were supplied as the sole electron acceptor and donor, respectively, suggesting that microbial azoreduction is an electron transport process and that this electron transport can yield energy to support growth. Purified membranous, periplasmic, and cytoplasmic fractions from S12 were analyzed, but only the membranous fraction was capable of reducing azo dyes with formate, lactate, pyruvate, or H2 as the electron donor. The presence of 5 μM Cu2+ ions, 200 μM dicumarol, 100 μM stigmatellin, and 100 μM metyrapone inhibited anaerobic azoreduction activity by both whole cells and the purified membrane fraction, showing that dehydrogenases, cytochromes, and menaquinone are essential electron transfer components for azoreduction. These results provide evidence that the microbial anaerobic azoreduction is linked to the electron transport chain and suggest that the dissimilatory azoreduction is a form of microbial anaerobic respiration. These findings not only expand the number of potential electron acceptors known for microbial energy conservation but also elucidate the mechanisms of microbial anaerobic azoreduction.

scholarly journals Hypoxia

2020 ◽  
pp. S157-S160
Author(s):  
M Stubbs
Keyword(s):  
Oxidative Phosphorylation ◽  
Adenosine Triphosphate ◽  
Electron Acceptor ◽  
Aerobic Respiration ◽  
Metabolic Processes ◽  
Terminal Electron Acceptor

Oxygen (O2) is the most commonly used drug in medicine and in anaesthesia. It is vital for all aerobic respiration in humans where it acts as the terminal electron acceptor during oxidative phosphorylation, resulting in the synthesis of adenosine triphosphate (ATP). This in turn supplies energy to all the body’s metabolic processes.

scholarly journals Oxygen restriction generates difficult-to-culture pathogens

2018 ◽  
Author(s):  
Lasse Kvich ◽  
Blaine G. Fritz ◽  
Stephanie Crone ◽  
Kasper N. Kragh ◽  
Mette Kolpen ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Molecular Oxygen ◽  
Electron Acceptor ◽  
Staphylococcus Epidermidis ◽  
Anaerobic Respiration ◽  
Clinical Samples ◽  
Culturable Bacteria ◽  
Chronic Infections ◽  
Anoxic Conditions

AbstractInduction of a non-culturable state has been demonstrated for many bacteria. In a clinical perspective, the lack of growth due to these non-culturable bacteria can have major consequences for the diagnosis and treatment of patients. Here we show how anoxic conditioning (restriction of molecular oxygen, O2) generates difficult-to-culture (DTC) bacteria during biofilm growth. A significant subpopulation of Pseudomonas aeruginosa entered a DTC state after anoxic conditioning, ranging from five to 90 % of the total culturable population, in both planktonic and biofilm models. Anoxic conditioning also generated DTC subpopulations of Staphylococcus aureus and Staphylococcus epidermidis. Growth of the DTC populations were achieved by substituting O2 with 10 mM NO3- as an alternative electron acceptor for anaerobic respiration or, in the case of P. aeruginosa, by adding sodium pyruvate or catalase as scavengers against reactive oxygen species (ROS) during aerobic respiration. An increase in normoxic plating due to addition of catalase suggests the molecule hydrogen peroxide as a possible mechanism for induction of DTC P. aeruginosa. Anoxic conditioning also generated a true viable but non-culturable (VBNC) population of P. aeruginosa that was not resurrected by substituting O2 with NO3- during anaerobic respiration. Moreover, bacterial detection in clinical samples was improved significantly by supplementing 10 mM NO3- to LB plates and incubating under anoxic conditions. These results demonstrate that habituation to an infectious anoxic micro-environment complicates diagnostic culturing of bacteria, especially in the case of chronic infections where oxygen is restricted due to the host immune response.ImportanceDiagnostics of bacteria from chronic infections by standard culture-based methods is challenging. Bacteria in a non-culturable state may contribute to the lack of culturing from these infections. Many stressors are known to induce a non-culturable state, among others the absence of molecular oxygen, which is evident in chronic infections due to high rates of oxygen consumption by the host response. In this study, we have shown that Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis can enter a difficult-to-culture state after oxygen restriction. Regrowth was not possible using conventional normoxic plating where oxygen served as electron acceptor. Instead, regrowth was enabled during anoxic conditions with added nitrate as alternative electron acceptor. Our findings show that bacteria can habituate to their environment and that it has to be taken into consideration especially when culturing clinical samples e.g. from chronic infections.

Fumarate is a terminal electron acceptor in the mammalian electron transport chain

Science ◽  
2021 ◽  
Vol 374 (6572) ◽  
pp. 1227-1237
Author(s):  
Jessica B. Spinelli ◽  
Paul C. Rosen ◽  
Hans-Georg Sprenger ◽  
Anna M. Puszynska ◽  
Jessica L. Mann ◽  
...  
Keyword(s):  
Electron Transport ◽  
Electron Acceptor ◽  
Electron Transport Chain ◽  
Terminal Electron Acceptor ◽  
Transport Chain

The influence of potassium dichromate on dissimilatory reduction of sulfate and nitrate ions by bacteria Desulfovibrio sp.

2017 ◽  
Vol 28 (1-2) ◽  
pp. 84-95
Author(s):  
O. M. Moroz ◽  
S. O. Hnatush ◽  
Ch. I. Bohoslavets ◽  
T. M. Hrytsun’ ◽  
B. M. Borsukevych
Keyword(s):  
Electron Acceptor ◽  
Potassium Dichromate ◽  
Anaerobic Respiration ◽  
Sulfate Reducing Bacteria ◽  
Negative Influence ◽  
Electron Acceptors ◽  
Metal Compounds ◽  
Nitrate Ions ◽  
Sulfate Reducing ◽  
Reducing Bacteria

Sulfate reducing bacteria, capable to reductive transformation of different nature pollutants, used in biotechnologies of purification of sewage, contaminated by carbon, sulfur, nitrogen and metal compounds. H2S formed by them sediment metals to form of insoluble sulfides. Number of metals can be used by these microorganisms as electron acceptors during anaerobic respiration. Because under the influence of metal compounds observed slowing of bacteria metabolism, selection isolated from technologically modified ecotops resistant to pollutions strains is important task to create a new biotechnologies of purification. That’s why the purpose of this work was to study the influence of potassium dichromate, present in medium, on reduction of sulfate and nitrate ions by sulfate reducing bacteria Desulfovibrio desulfuricans IMV K-6, Desulfovibrio sp. Yav-6 and Desulfovibrio sp. Yav-8, isolated from Yavorivske Lake, to estimate the efficiency of possible usage of these bacteria in technologies of complex purification of environment from dangerous pollutants. Bacteria were cultivated in modified Kravtsov-Sorokin medium without SO42- and FeCl2×4H2O for 10 days. To study the influence of K2Cr2O7 on usage by bacteria SO42- or NO3- cells were seeded to media with Na2SO4×10H2O or NaNO3 and K2Cr2O7 at concentrations of 1.74 mM for total content of electron acceptors in medium 3.47 mM (concentration of SO42- in medium of standard composition). Cells were also seeded to media with 3.47 mM Na2SO4×10H2O, NaNO3 or K2Cr2O7 to investigate their growth in media with SO42-, NO3- or Cr2O72- as sole electron acceptor (control). Biomass was determined by turbidymetric method, content of sulfate, nitrate, dichromate, chromium (III) ions, hydrogen sulfide or ammonia ions in cultural liquid – by spectrophotometric method. It was found that K2Cr2O7 inhibits growth (2.2 and 1.3 times) and level of reduction by bacteria sulfate or nitrate ions (4.2 and 3.0 times, respectively) at simultaneous addition into cultivation medium of 1.74 mM SO42- or NO3- and 1.74 mM Cr2O72-, compared with growth and level of reduction of sulfate or nitrate ions in medium only with SO42- or NO3- as sole electron acceptor. Revealed that during cultivation of bacteria in presence of equimolar amount of SO42- or NO3- and Cr2O72-, last used by bacteria faster, content of Cr3+ during whole period of bacteria cultivation exceeded content H2S or NH4+. K2Cr2O7 in medium has most negative influence on dissimilatory reduction by bacteria SO42- than NO3-, since level of nitrate ions reduction by cells in medium with NO3- and Cr2O72- was a half times higher than level of sulfate ions reduction by it in medium with SO42- and Cr2O72-. The ability of bacteria Desulfovibrio sp. to priority reduction of Cr2O72- and after their exhaustion − NO3- and SO42- in the processes of anaerobic respiration can be used in technologies of complex purification of environment from toxic compounds.

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