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Anaerobic respiration

Zhen Yan, Prachi Joshi, Christopher A Gorski, James G Ferry
Consumption of methane by aerobic and anaerobic microbes governs the atmospheric level of this powerful greenhouse gas. Whereas a biochemical understanding of aerobic methanotrophy is well developed, a mechanistic understanding of anaerobic methanotrophy has been prevented by the unavailability of pure cultures. Here we report a biochemical investigation of Methanosarcina acetivorans, a methane-producing species capable of anaerobic methanotrophic growth dependent on reduction of Fe(III). Our findings support a pathway anchored by Fe(III)-dependent mechanisms for energy conservation driving endergonic reactions that are key to methanotrophic growth...
April 24, 2018: Nature Communications
Pallabini Dash, M Bala Divya, Lalitha Guruprasad, Kunchur Guruprasad
BACKGROUND: Earlier based on bioinformatics analyses, we had predicted the Mycobacterium tuberculosis (M.tb) proteins; Rv1555 and Rv1554, among the potential new tuberculosis drug targets. According to the 'TB-drugome' the Rv1555 protein is 'druggable' with sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra) drugs. In the present work, we intended to understand via computer modeling studies, how the above drugs are likely to inhibit the M.tb protein's function. RESULTS: The three-dimensional computer models for M...
April 18, 2018: BMC Structural Biology
Ran Zhou, Yan Zhang, Guizhen Du, Li Han, Sinian Zheng, Jian Liang, Xiaomin Huang, Yufeng Qin, Wei Wu, Minjian Chen, Di Wu, Ling Song, Guangbo Fu, Shuyan Lv, Yankai Xia, Chuncheng Lu, Xinru Wang
Glycolysis, through anaerobic respiration, can supply energy for human sperm motility. MicroRNAs (miRNAs) could participate in the glycolytic pathway through regulating target genes. To investigate the potential role of glycolysis-related miRNAs in asthenozoospermia, TaqMan Low Density Array (TLDA) was used to screen potentially functional miRNAs, and seven glycolysis-related miRNAs were isolated to be related to asthenozoospermia. After qRT-PCR validation, only one seminal plasma miRNA, let-7b-5p, was found significantly decreased in severe asthenozoospermia cases compared with healthy controls...
April 10, 2018: Gene
Sadia Afrin, Francesca Giampieri, Massimiliano Gasparrini, Tamara Y Forbes-Hernández, Danila Cianciosi, Patricia Reboredo-Rodriguez, Piera Pia Manna, Jiaojiao Zhang, Josè L Quiles, Maurizio Battino
Despite its high content of phenolic compounds, the chemopreventive activity of Manuka honey (MH) is still elusive. The aim of the present work was to evaluate the effects of MH on oxidative stress, antioxidant enzymes, cellular metabolism and the metastatic ability in HCT-116 and LoVo cells, paying particular attention to the molecular mechanisms involved. We observed a strong induction of oxidative stress after MH treatment since it augmented the accumulation of reactive oxygen species and increased the damage to proteins, lipids and DNA...
April 12, 2018: Food & Function
G B Postnikova, E A Shekhovtsova
In this review, we shortly summarize the data of our studies (and also corresponding studies of other authors) on the new mechanism of myoglobin (Mb) deoxygenation in a cell, according to which Mb acts as an oxygen transporter, and its affinity for the ligand, like in other transporting proteins, is regulated by the interaction with the target, in our case, mitochondria (Mch). We firstly found that contrary to previously formulated and commonly accepted concepts, oxymyoglobin (MbO2 ) deoxygenation occurs only via interaction of the protein with respiring mitochondria (low pO2 values are necessary but not sufficient for this process to proceed)...
February 2018: Biochemistry. Biokhimii︠a︡
Elliot S Friedman, Kyle Bittinger, Tatiana V Esipova, Likai Hou, Lillian Chau, Jack Jiang, Clementina Mesaros, Peder J Lund, Xue Liang, Garret A FitzGerald, Mark Goulian, Daeyeon Lee, Benjamin A Garcia, Ian A Blair, Sergei A Vinogradov, Gary D Wu
The succession from aerobic and facultative anaerobic bacteria to obligate anaerobes in the infant gut along with the differences between the compositions of the mucosally adherent vs. luminal microbiota suggests that the gut microbes consume oxygen, which diffuses into the lumen from the intestinal tissue, maintaining the lumen in a deeply anaerobic state. Remarkably, measurements of luminal oxygen levels show nearly identical pO2 (partial pressure of oxygen) profiles in conventional and germ-free mice, pointing to the existence of oxygen consumption mechanisms other than microbial respiration...
April 2, 2018: Proceedings of the National Academy of Sciences of the United States of America
Maria Marín, Adriana Artola, Antoni Sánchez
Production of enzymes through solid-state fermentation (SSF) of agro-industrial wastes reports high productivity with low investment. The extraction of the final product from the solid waste and solid disposal represent the main cost of the process. In this work, the complete downstream processes of SSF of two industrial residues for the production of proteases, soy fibre (SF) and a mixture of hair and sludge (HS), were studied in terms of activity recovery, using different extraction parameters (extracting solvent, ratio solid: solvent and extraction mode)...
April 2018: 3 Biotech
H Sekiguchi, Y Tamaki, Y Kondo, H Nakamura, K Hanashiro, K Yonemoto, T Moritani, I Kukita
This study aimed to evaluate neuromuscular activation in the scalene and sternocleidomastoid muscles using surface electromyography (EMG) during progressively increased inspiratory flow, produced by increasing the respiratory rate under inspiratory-resistive loading using a mask ventilator. Moreover, we attempted to identify the EMG inflection point (EMGIP ) on the graph, at which the root mean square (RMS) of the EMG signal values of the inspiratory muscles against the inspiratory flow velocity acceleration abruptly increases, similarly to the EMG anaerobic threshold (EMGAT ) reported during incremental-resistive loading in other skeletal muscles...
March 1, 2018: Physiology International
Wolfgang Buckel, Rudolf K Thauer
Flavin-based electron bifurcation is a newly discovered mechanism, by which a hydride electron pair from NAD(P)H, coenzyme F420 H2 , H2 , or formate is split by flavoproteins into one-electron with a more negative reduction potential and one with a more positive reduction potential than that of the electron pair. Via this mechanism microorganisms generate low- potential electrons for the reduction of ferredoxins (Fd) and flavodoxins (Fld). The first example was described in 2008 when it was found that the butyryl-CoA dehydrogenase-electron-transferring flavoprotein complex (Bcd-EtfAB) of Clostridium kluyveri couples the endergonic reduction of ferredoxin (E0 ' = -420 mV) with NADH (-320 mV) to the exergonic reduction of crotonyl-CoA to butyryl-CoA (-10 mV) with NADH...
2018: Frontiers in Microbiology
Leonie Venter, Du Toit Loots, Lodewyk J Mienie, Peet J Jansen van Rensburg, Shayne Mason, Andre Vosloo, Jeremie Z Lindeque
Functional hypoxia is a stress condition caused by the abalone itself as a result of increased muscle activity, which generally necessitates the employment of anaerobic metabolism if the activity is sustained for prolonged periods. With that being said, abalone are highly reliant on anaerobic metabolism to provide partial compensation for energy production during oxygen-deprived episodes. However, current knowledge on the holistic metabolic response for energy metabolism during functional hypoxia, and the contribution of different metabolic pathways and various abalone tissues towards the overall accumulation of anaerobic end-products in abalone are scarce...
March 23, 2018: Biology Open
Carmina Angelica Perez-Romero, Maxime Lalonde, Pascal Chartrand, Emilio Cusanelli
Telomeres are maintained in a heterochromatic state that represses transcription of subtelomeric genes, a phenomenon known as telomere position effect. Nevertheless, telomeric DNA is actively transcribed, leading to the synthesis of telomeric repeat-containing noncoding RNA or TERRA. This nuclear noncoding RNA has been proposed to play important roles at telomeres, regulating their silencing, capping, repair and elongation by telomerase. In the budding yeast Saccharomyces cerevisiae, TERRA accumulation is repressed by telomeric silencing and the Rat1 exonuclease...
March 22, 2018: Current Genetics
Stephen E Beaton, Rhiannon M Evans, Alexander J Finney, Ciaran M Lamont, Fraser A Armstrong, Frank Sargent, Stephen B Carr
Under anaerobic conditions Escherichia coli is able to metabolize molecular hydrogen via the action of several [NiFe]-hydrogenase enzymes. Hydrogenase-2, which is typically present in cells at low levels during anaerobic respiration, is a periplasmic-facing membrane-bound complex that functions as a proton pump to convert energy from H2 oxidation into a proton gradient; consequently, its structure is of great interest. Empirically, the complex consists of a tightly-bound core catalytic module, comprising large (HybC) and small (HybO) subunits, which is attached to an Fe-S protein (HybA) and an integral membrane protein, HybB...
March 19, 2018: Biochemical Journal
Silvia Ravera, Maria Grazia Signorello, Martina Bartolucci, Sara Ferrando, Lucia Manni, Federico Caicci, Daniela Calzia, Isabella Panfoli, Alessandro Morelli, Giuliana Leoncini
BACKGROUND INFORMATION: Energy demand in human platelets is very high, to carry out their functions. As for most human cells, the aerobic metabolism represents the primary energy source in platelets, even though mitochondria are negligibly represented. Following the hypothesis that other structures could be involved in chemical energy production, in this work, we have investigated the functional expression of an extramitochondrial aerobic metabolism in platelets. RESULTS: Oximetric and luminometric analyses showed that platelets consume large amounts of oxygen and produce ATP in the presence of common respiring substrates, such as pyruvate + malate or succinate, although morphological electron microscopy analysis showed that these contain few mitochondria...
March 14, 2018: Biology of the Cell
A C Van Erp, R A Rebolledo, D Hoeksma, N R Jespersen, P J Ottens, R Nørregaard, M Pedersen, C Laustsen, J G M Burgerhof, J C Wolters, J Ciapaite, H E Bøtker, H G D Leuvenink, B Jespersen
Hepatic and renal energy status prior to transplantation correlates with graft survival. However, effects of brain death (BD) on organ-specific energy status are largely unknown. We studied metabolism, perfusion, oxygen consumption, and mitochondrial function in the liver and kidneys following BD. BD was induced in mechanically-ventilated rats, inflating an epidurally-placed Fogarty-catheter, with sham-operated rats as controls. A 9.4T-preclinical MRI system measured hourly oxygen availability (BOLD-related R2*) and perfusion (T1-weighted)...
March 13, 2018: Scientific Reports
Kevin W Becker, Felix J Elling, Jan M Schröder, Julius S Lipp, Tobias Goldhammer, Matthias Zabel, Marcus Elvert, Jörg Overmann, Kai-Uwe Hinrichs
The stratified water column of the Black Sea serves as a model ecosystem for studying the interactions of microorganisms with major biogeochemical cycles. Here we provide detailed analysis of isoprenoid quinones to study microbial redox processes in the ocean. In a continuum from the photic zone through the chemocline into deep anoxic sediments of the southern Black Sea, diagnostic quinones and inorganic geochemical parameters indicate niche segregation between redox processes and corresponding shifts in microbial community composition...
March 9, 2018: Applied and Environmental Microbiology
Omar Federico Ordoñez, María Cecilia Rasuk, Mariana Noelia Soria, Manuel Contreras, María Eugenia Farías
Biofilms, microbial mats, and microbialites dwell under highly limiting conditions (high salinity, extreme aridity, pH, and elevated arsenic concentration) in the Andean Puna. Only recent pioneering studies have described the microbial diversity of different Altiplano lakes and revealed their unexpectedly diverse microbial communities. Arsenic metabolism is proposed to be an ancient mechanism to obtain energy by microorganisms. Members of Bacteria and Archaea are able to exploit arsenic as a bioenergetic substrate in either anaerobic arsenate respiration or chemolithotrophic growth on arsenite...
March 8, 2018: Microbial Ecology
Géraldine Florence Buttet, Alexandra Marie Murray, Tobias Goris, Mélissa Burion, Biao Jin, Massimo Rolle, Christof Holliger, Julien Maillard
Two anaerobic bacterial consortia, each harboring a distinct Sulfurospirillum population, were derived from a ten year old consortium, SL2, previously characterized for the stepwise dechlorination of tetrachloroethene (PCE) to cis-dichloroethene (cis-DCE) via accumulation of trichloroethene (TCE). Population SL2-1 dechlorinated PCE to TCE exclusively, while SL2-2 produced cis-DCE from PCE without substantial TCE accumulation. The reasons explaining the long-term coexistence of the populations were investigated...
March 6, 2018: FEMS Microbiology Ecology
S Kushwaha, A K Marcus, B E Rittmann
In situ bioreduction of soluble hexavalent uranium [U(VI)] to insoluble U(IV) (as UO2 ) has been proposed as a means of preventing U migration in the groundwater. This work focuses on the bioreduction of U(VI) and precipitation of U(IV). It uses anaerobic batch reactors with Desulfovibrio vulgaris, a well-known sulfate, iron, and U(VI) reducer, growing on lactate as the electron donor, in the absence of sulfate, and with a 30-mM bicarbonate buffering. In the absence of sulfate, D. vulgaris reduced >90% of the total soluble U(VI) (1 mM) to form U(IV) solids that were characterized by X-ray diffraction and confirmed to be nano-crystalline uraninite with crystallite size 2...
February 24, 2018: Biotechnology and Bioengineering
Bela Hausmann, Claus Pelikan, Craig W Herbold, Stephan Köstlbacher, Mads Albertsen, Stephanie A Eichorst, Tijana Glavina Del Rio, Martin Huemer, Per H Nielsen, Thomas Rattei, Ulrich Stingl, Susannah G Tringe, Daniela Trojan, Cecilia Wentrup, Dagmar Woebken, Michael Pester, Alexander Loy
Sulfur-cycling microorganisms impact organic matter decomposition in wetlands and consequently greenhouse gas emissions from these globally relevant environments. However, their identities and physiological properties are largely unknown. By applying a functional metagenomics approach to an acidic peatland, we recovered draft genomes of seven novel Acidobacteria species with the potential for dissimilatory sulfite (dsrAB, dsrC, dsrD, dsrN, dsrT, dsrMKJOP) or sulfate respiration (sat, aprBA, qmoABC plus dsr genes)...
February 23, 2018: ISME Journal
Xiao Deng, Naoshi Dohmae, Kenneth H Nealson, Kazuhito Hashimoto, Akihiro Okamoto
Bacterial reduction of oxidized sulfur species (OSS) is critical for energy production in anaerobic marine subsurfaces. In organic-poor sediments, H2 has been considered as a major energy source for bacterial respiration. We identified outer-membrane cytochromes (OMCs) that are broadly conserved in sediment OSS-respiring bacteria and enable cells to directly use electrons from insoluble minerals via extracellular electron transport. Biochemical, transcriptomic, and microscopic analyses revealed that the identified OMCs were highly expressed on the surface of cells and nanofilaments in response to electron donor limitation...
February 2018: Science Advances
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