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Environmental Microbiology Jun 2021Dysoxic marine waters (DMW, < 1 μM oxygen) are currently expanding in volume in the oceans, which has biogeochemical, ecological and societal consequences on a... (Review)
Review
Dysoxic marine waters (DMW, < 1 μM oxygen) are currently expanding in volume in the oceans, which has biogeochemical, ecological and societal consequences on a global scale. In these environments, distinct bacteria drive an active sulfur cycle, which has only recently been recognized for open-ocean DMW. This review summarizes the current knowledge on these sulfur-cycling bacteria. Critical bottlenecks and questions for future research are specifically addressed. Sulfate-reducing bacteria (SRB) are core members of DMW. However, their roles are not entirely clear, and they remain largely uncultured. We found support for their remarkable diversity and taxonomic novelty by mining metagenome-assembled genomes from the Black Sea as model ecosystem. We highlight recent insights into the metabolism of key sulfur-oxidizing SUP05 and Sulfurimonas bacteria, and discuss the probable involvement of uncultivated SAR324 and BS-GSO2 bacteria in sulfur oxidation. Uncultivated Marinimicrobia bacteria with a presumed organoheterotrophic metabolism are abundant in DMW. Like SRB, they may use specific molybdoenzymes to conserve energy from the oxidation, reduction or disproportionation of sulfur cycle intermediates such as S and thiosulfate, produced from the oxidation of sulfide. We expect that tailored sampling methods and a renewed focus on cultivation will yield deeper insight into sulfur-cycling bacteria in DMW.
Topics: Bacteria; Ecosystem; Metagenome; Oxidation-Reduction; Oxygen; Seawater; Sulfur
PubMed: 33000514
DOI: 10.1111/1462-2920.15265 -
International Microbiology : the... Sep 2015In nature, highly efficient and diverse consortia of microbes cycle carbon and other elements while generating energy for growth. Driving these reactions are organisms... (Review)
Review
In nature, highly efficient and diverse consortia of microbes cycle carbon and other elements while generating energy for growth. Driving these reactions are organisms with the ability to extract electrons from the chemical substrates and transfer them to insoluble and soluble electron acceptors. One bacterial group in particular, Geobacter spp., can couple their respiratory metabolism to the reduction of insoluble minerals, such as iron and manganese oxides, and soluble toxic metals such as uranium. Key to these activities is the ability of the cells to transfer respiratory electrons extracellularly using an electroactive cell envelope containing abundant metalloproteins, including c-cytochromes, and conductive protein appendages or pili (known as nanowires). Thus, in addition to been ecological drivers of the cycling of carbon and metals in nature, these organisms show promise for the bioremediation of environments impacted with toxic metals. The electrical activity of Geobacter can also be mimicked in electrochemical reactors equipped with an electrode poised at a metabolically oxidizing potential, so that the electrode functions as an unlimited sink of electrons to drive the oxidation of electron donors and support cell growth. Electrochemical reactors are promising for the treatments of agricultural, industrial, and human wastes, and the electroactivity of these microbes can be used to develop materials and devices for bioenergy and bioremediation applications.
Topics: Biotechnology; Electricity; Electron Transport; Geobacter; Oxidation-Reduction
PubMed: 27036742
DOI: 10.2436/20.1501.01.245 -
Current Hypertension Reports Dec 2021In this article, we summarize the current literature supporting metabolic and redox signaling pathways as important mechanisms underlying T cell activation in the... (Review)
Review
PURPOSE OF REVIEW
In this article, we summarize the current literature supporting metabolic and redox signaling pathways as important mechanisms underlying T cell activation in the context of hypertension.
RECENT FINDINGS
T cell immunometabolism undergoes dramatic remodeling in order to meet the demands of T cell activation, differentiation, and proliferation. Recent evidence demonstrates that the T cell oxidation-reduction (redox) system also undergoes significant changes upon activation, which can itself modulate metabolic processes and T cell function. Dysregulation of these signaling pathways can lead to aberrant T cell activation and inappropriate ROS production, both of which are linked to pathological conditions like hypertension. While the contribution of T cells to the progression of hypertension has been thoroughly investigated, how T cell metabolism and redox signaling changes, both separately and together, is an area of study that remains largely untouched. This review presents evidence from our own laboratory as well as others to highlight the importance of these two mechanisms in the study of hypertension.
Topics: Humans; Hypertension; Oxidation-Reduction; Reactive Oxygen Species; Signal Transduction; T-Lymphocytes
PubMed: 34888745
DOI: 10.1007/s11906-021-01162-5 -
International Journal of Molecular... Apr 2022Oxidative phosphorylation is an efficient way to generate the cellular energy currency ATP in a cascade of redox reactions, which ultimately terminate in the reduction...
Oxidative phosphorylation is an efficient way to generate the cellular energy currency ATP in a cascade of redox reactions, which ultimately terminate in the reduction of molecular oxygen to water [...].
Topics: Homeostasis; Oxidation-Reduction; Oxidative Phosphorylation; Oxygen; Oxygen Consumption; Reactive Oxygen Species
PubMed: 35562895
DOI: 10.3390/ijms23094505 -
Proceedings of the National Academy of... Oct 2022Constructing redox semiconductor heterojunction photocatalysts is the most effective and important means to complete the artificial photosynthetic overall reaction...
Constructing redox semiconductor heterojunction photocatalysts is the most effective and important means to complete the artificial photosynthetic overall reaction (i.e., coupling CO photoreduction and water photo-oxidation reactions). However, multiphase hybridization essence and inhomogeneous junction distribution in these catalysts extremely limit the diverse design and regulation of the modes of photogenerated charge separation and transfer pathways, which are crucial factors to improve photocatalytic performance. Here, we develop molecular oxidation-reduction (OR) junctions assembled with oxidative cluster (PMo, for water oxidation) and reductive cluster (Ni, for CO reduction) in a direct (-OR), alternant (-OR), or symmetric (-OR) manner, respectively, for artificial photosynthesis. Significantly, the transfer direction and path of photogenerated charges between traditional junctions are obviously reformed and enriched in these well-defined crystalline catalysts with monophase periodic distribution and thus improve the separation efficiency of the electrons and holes. In particular, the charge migration in -OR shows a periodically and continuously opposite mode. It can inhibit the photogenerated charge recombination more effectively and enhance the photocatalytic performance largely when compared with the traditional heterojunction models. Structural analysis and density functional theory calculations disclose that, through adjusting the spatial arrangement of oxidation and reduction clusters, the energy level and population of the orbitals of these OR junctions can be regulated synchronously to further optimize photocatalytic performance. The establishment of molecular OR junctions is a pioneering important discovery for extremely improving the utilization efficiency of photogenerated charges in the artificial photosynthesis overall reaction.
Topics: Carbon Dioxide; Light; Oxidation-Reduction; Photosynthesis; Water
PubMed: 36161955
DOI: 10.1073/pnas.2210550119 -
Nature Reviews. Immunology Aug 2016Ageing, infections and inflammation result in oxidative stress that can irreversibly damage cellular structures. The oxidative damage of lipids in membranes or... (Review)
Review
Ageing, infections and inflammation result in oxidative stress that can irreversibly damage cellular structures. The oxidative damage of lipids in membranes or lipoproteins is one of these deleterious consequences that not only alters lipid function but also leads to the formation of neo-self epitopes - oxidation-specific epitopes (OSEs) - which are present on dying cells and damaged proteins. OSEs represent endogenous damage-associated molecular patterns that are recognized by pattern recognition receptors and the proteins of the innate immune system, and thereby enable the host to sense and remove dangerous biological waste and to maintain homeostasis. If this system is dysfunctional or overwhelmed, the accumulation of OSEs can trigger chronic inflammation and the development of diseases, such as atherosclerosis and age-related macular degeneration. Understanding the molecular components and mechanisms that are involved in this process will help to identify individuals with an increased risk of developing chronic inflammation, and will also help to indicate novel modes of therapeutic intervention.
Topics: Animals; Disease Susceptibility; Epitopes; Homeostasis; Humans; Immunity, Cellular; Immunity, Humoral; Immunity, Innate; Lipid Metabolism; Lipid Peroxidation; Oxidation-Reduction; Oxidative Stress
PubMed: 27346802
DOI: 10.1038/nri.2016.63 -
Journal of Industrial Microbiology &... Jul 2022Microbial biofilms are ubiquitous. In marine and freshwater ecosystems, microbe-mineral interactions sustain biogeochemical cycles, while biofilms found on plants and... (Review)
Review
Microbial biofilms are ubiquitous. In marine and freshwater ecosystems, microbe-mineral interactions sustain biogeochemical cycles, while biofilms found on plants and animals can range from pathogens to commensals. Moreover, biofouling and biocorrosion represent significant challenges to industry. Bioprocessing is an opportunity to take advantage of biofilms and harness their utility as a chassis for biocommodity production. Electrochemical bioreactors have numerous potential applications, including wastewater treatment and commodity production. The literature examining these applications has demonstrated that the cell-surface interface is vital to facilitating these processes. Therefore, it is necessary to understand the state of knowledge regarding biofilms' role in bioprocessing. This mini-review discusses bacterial biofilm formation, cell-surface redox interactions, and the role of microbial electron transfer in bioprocesses. It also highlights some current goals and challenges with respect to microbe-mediated bioprocessing and future perspectives.
Topics: Bioelectric Energy Sources; Biofilms; Ecosystem; Electrodes; Electron Transport; Electrons; Oxidation-Reduction
PubMed: 35381088
DOI: 10.1093/jimb/kuac012 -
Journal of the American Chemical Society Nov 2022Alcohol oxidation is an important class of reaction that is traditionally performed under harsh conditions and most often requires the use of organometallic compounds or...
Alcohol oxidation is an important class of reaction that is traditionally performed under harsh conditions and most often requires the use of organometallic compounds or transition metal complexes as catalysts. Here, we introduce a new electrochemical synthetic method, referred to as reductive oxidation, in which alcohol oxidation is initiated by the redox-mediated electrocatalytic reduction of peroxydisulfate to generate the highly oxidizing sulfate radical anion. Thus, and counter-intuitively, alcohol oxidation occurs as a result of an electrochemical reduction reaction. This approach provides a selective synthetic route for the oxidation of alcohols carried out under mild conditions to aldehydes, ketones, and carboxylic acids with up to 99% conversion yields. First-principles density functional theory calculations, ab initio molecular dynamics simulations, cyclic voltammetry, and finite difference simulations are presented that support and provide additional insights into the SO-mediated oxidation of benzyl alcohol to benzaldehyde.
Topics: Alcohols; Oxidation-Reduction; Ketones; Catalysis; Aldehydes
PubMed: 36346612
DOI: 10.1021/jacs.2c07305 -
Journal of Inorganic Biochemistry Aug 2021It is well known that bacteria and fungi have evolved sophisticated systems for acquiring the abundant but biologically inaccessible trace element iron. These systems... (Review)
Review
It is well known that bacteria and fungi have evolved sophisticated systems for acquiring the abundant but biologically inaccessible trace element iron. These systems are based on high affinity Fe(III)-specific binding compounds called siderophores which function to acquire, transport, and process this essential metal ion. Many hundreds of siderophores are now known and their numbers continue to grow. Extensive studies of their isolation, structure, transport, and molecular genetics have been undertaken in the last three decades and have been comprehensively reviewed many times. In this review we focus on a unique subset of siderophores that has only been recognized in the last 20 years, namely those whose iron complexes display photoactivity. This photoactivity, which typically results in the photooxidation of the siderophore ligand with concomitant reduction of Fe(III) to Fe(II), seemingly upsets the siderophore paradigm of forming and transporting only extremely stable Fe(III) complexes into microbial cells. Here we review their structure, synthesis, photochemistry, photoproduct coordination chemistry and explore the potential biological and ecological consequences of this photoactivity.
Topics: Bacteria; Coordination Complexes; Fungi; Iron; Light; Molecular Structure; Oxidation-Reduction; Siderophores
PubMed: 34010741
DOI: 10.1016/j.jinorgbio.2021.111457 -
Molecules (Basel, Switzerland) Jun 2021Laccases are multicopper oxidases that have shown a great potential in various biotechnological and green chemistry processes mainly due to their high relative... (Review)
Review
Laccases are multicopper oxidases that have shown a great potential in various biotechnological and green chemistry processes mainly due to their high relative non-specific oxidation of phenols, arylamines and some inorganic metals, and their high redox potentials that can span from 500 to 800 mV vs. SHE. Other advantages of laccases include the use of readily available oxygen as a second substrate, the formation of water as a side-product and no requirement for cofactors. Importantly, addition of low-molecular-weight redox mediators that act as electron shuttles, promoting the oxidation of complex bulky substrates and/or of higher redox potential than the enzymes themselves, can further expand their substrate scope, in the so-called laccase-mediated systems (LMS). Laccase bioprocesses can be designed for efficiency at both acidic and basic conditions since it is known that fungal and bacterial laccases exhibit distinct optimal pH values for the similar phenolic and aromatic amines. This review covers studies on the synthesis of five- and six-membered ring heterocyclic cores, such as benzimidazoles, benzofurans, benzothiazoles, quinazoline and quinazolinone, phenazine, phenoxazine, phenoxazinone and phenothiazine derivatives. The enzymes used and the reaction protocols are briefly outlined, and the mechanistic pathways described.
Topics: Bacteria; Biocatalysis; Fungi; Heterocyclic Compounds; Laccase; Oxidation-Reduction
PubMed: 34207073
DOI: 10.3390/molecules26123719