scholarly journals Phenazines and Other Redox-Active Antibiotics Promote Microbial Mineral Reduction

2004 ◽  
Vol 70 (2) ◽  
pp. 921-928 ◽  
Author(s):  
Maria E. Hernandez ◽  
Andreas Kappler ◽  
Dianne K. Newman
Keyword(s):  
Natural Products ◽  
Manganese Oxides ◽  
Ferric Iron ◽  
Shewanella Oneidensis ◽  
Iron Chelator ◽  
Redox Potentials ◽  
Bacterial Strains ◽  
Redox Active ◽  
Therapeutic Properties ◽  
Iron And Manganese

ABSTRACT Natural products with important therapeutic properties are known to be produced by a variety of soil bacteria, yet the ecological function of these compounds is not well understood. Here we show that phenazines and other redox-active antibiotics can promote microbial mineral reduction. Pseudomonas chlororaphis PCL1391, a root isolate that produces phenazine-1-carboxamide (PCN), is able to reductively dissolve poorly crystalline iron and manganese oxides, whereas a strain carrying a mutation in one of the phenazine-biosynthetic genes (phzB) is not; the addition of purified PCN restores this ability to the mutant strain. The small amount of PCN produced relative to the large amount of ferric iron reduced in cultures of P. chlororaphis implies that PCN is recycled multiple times; moreover, poorly crystalline iron (hydr)oxide can be reduced abiotically by reduced PCN. This ability suggests that PCN functions as an electron shuttle rather than an iron chelator, a finding that is consistent with the observation that dissolved ferric iron is undetectable in culture fluids. Multiple phenazines and the glycopeptidic antibiotic bleomycin can also stimulate mineral reduction by the dissimilatory iron-reducing bacterium Shewanella oneidensis MR1. Because diverse bacterial strains that cannot grow on iron can reduce phenazines, and because thermodynamic calculations suggest that phenazines have lower redox potentials than those of poorly crystalline iron (hydr)oxides in a range of relevant environmental pH (5 to 9), we suggest that natural products like phenazines may promote microbial mineral reduction in the environment.

scholarly journals Comparative insights into genome signatures of ferric iron oxide- and anode-stimulated Desulfuromonas spp. strains

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yong Guo ◽  
Tomo Aoyagi ◽  
Tomoyuki Hori
Keyword(s):  
Iron Oxide ◽  
Genome Rearrangement ◽  
Ferric Iron ◽  
Electron Acceptors ◽  
Extracellular Electron Transfer ◽  
Redox Potentials ◽  
Bacterial Strains ◽  
Biosynthesis Gene Cluster ◽  
Genomic Signatures ◽  
Flagellar Biosynthesis

Abstract Background Halotolerant Fe (III) oxide reducers affiliated in the family Desulfuromonadaceae are ubiquitous and drive the carbon, nitrogen, sulfur and metal cycles in marine subsurface sediment. Due to their possible application in bioremediation and bioelectrochemical engineering, some of phylogenetically close Desulfuromonas spp. strains have been isolated through enrichment with crystalline Fe (III) oxide and anode. The strains isolated using electron acceptors with distinct redox potentials may have different abilities, for instance, of extracellular electron transport, surface recognition and colonization. The objective of this study was to identify the different genomic signatures between the crystalline Fe (III) oxide-stimulated strain AOP6 and the anode-stimulated strains WTL and DDH964 by comparative genome analysis. Results The AOP6 genome possessed the flagellar biosynthesis gene cluster, as well as diverse and abundant genes involved in chemotaxis sensory systems and c-type cytochromes capable of reduction of electron acceptors with low redox potentials. The WTL and DDH964 genomes lacked the flagellar biosynthesis cluster and exhibited a massive expansion of transposable gene elements that might mediate genome rearrangement, while they were deficient in some of the chemotaxis and cytochrome genes and included the genes for oxygen resistance. Conclusions Our results revealed the genomic signatures distinctive for the ferric iron oxide- and anode-stimulated Desulfuromonas spp. strains. These findings highlighted the different metabolic abilities, such as extracellular electron transfer and environmental stress resistance, of these phylogenetically close bacterial strains, casting light on genome evolution of the subsurface Fe (III) oxide reducers.

The Impact of Oxides on Environmental Chemistry

2016 ◽  
Author(s):  
Bruce C. Bunker ◽  
William H. Casey
Keyword(s):  
Subduction Zones ◽  
Plate Tectonics ◽  
Manganese Oxides ◽  
Environmental Chemistry ◽  
Natural Environments ◽  
Chemical Transformations ◽  
Rock Types ◽  
Living Things ◽  
Redox Active ◽  
Iron And Manganese

The ancient Greek philosopher Empedocles defined our environments using the four basic elements of fire, earth, wind, and water. Although we now know there are at least 118 elements, of which 98 are naturally occurring, these ancient descriptions aptly describe the habitats on Earth that are occupied by oxides and living things. Many oxides that comprise Earth’s surface are born by the fire represented by the massive heat of Earth’s interior as mediated by plate tectonics. This heat produces the igneous rocks found in volcanoes and our major mountain chains. Water weathers these pristine rocks, which are gradually broken down to form earth, which includes the wide diversity of other rock types, soils, and sediments covering the surfaces of our continents and ocean floors. Weathered oxides in the form of dust are blown by wind and enter the atmosphere, where they influence the chemistry of the air we breathe and the rainfall that supports continental life. The chemical transformations of oxides are strongly influenced by all the environmental conditions they encounter in their life cycle (see Chapter 17). Conversely, the interactions between oxides, water, and organisms help define many of the environments that allow life on Earth to thrive. These interactions form the basis for this final chapter of our book. Oxides are present in all our planet’s major environments. In this chapter, we explore each of the environments defined by the ancient Greeks in descending order based on their distance from Earth’s core. The chapter progresses from the stratosphere (air) to continental surfaces (earth) to our oceans (water) and finally to the subsurface environments of subduction zones such as the Marianas Trench (fire). In each section, we highlight reactions involving the two most important classes of oxides in terms of their environmental impact, both of which are weathering products: (1) the clay minerals and (2) the redox-active colloids of iron and manganese oxides. Clay mineral reactions impact colloidal interactions (Chapter 8), ion exchange (Chapter 10), and the sequestration of environmental nutrients and contaminants. Reactions of the redox-active oxidates of iron and manganese are dominant in terms of reversible and often complex electrochemical (Chapter 11) and photochemical (Chapter 13) processes that take place in natural environments.

scholarly journals Respiration and Growth of Shewanella oneidensis MR-1 Using Vanadate as the Sole Electron Acceptor

2005 ◽  
Vol 187 (10) ◽  
pp. 3293-3301 ◽  
Author(s):  
Wesley Carpentier ◽  
Lina De Smet ◽  
Jozef Van Beeumen ◽  
Ann Brigé
Keyword(s):  
Electron Acceptor ◽  
Manganese Oxides ◽  
Proton Translocation ◽  
Shewanella Oneidensis ◽  
Anaerobic Respiration ◽  
Difference Spectra ◽  
Free Living ◽  
E Coli ◽  
Membrane Bound ◽  
Iron And Manganese

ABSTRACT Shewanella oneidensis MR-1 is a free-living gram-negative γ-proteobacterium that is able to use a large number of oxidizing molecules, including fumarate, nitrate, dimethyl sulfoxide, trimethylamine N-oxide, nitrite, and insoluble iron and manganese oxides, to drive anaerobic respiration. Here we show that S. oneidensis MR-1 is able to grow on vanadate as the sole electron acceptor. Oxidant pulse experiments demonstrated that proton translocation across the cytoplasmic membrane occurs during vanadate reduction. Proton translocation is abolished in the presence of protonophores and the inhibitors 2-heptyl-4-hydroxyquinoline N-oxide and antimycin A. Redox difference spectra indicated the involvement of membrane-bound menaquinone and cytochromes c, which was confirmed by transposon mutagenesis and screening for a vanadate reduction-deficient phenotype. Two mutants which are deficient in menaquinone synthesis were isolated. Another mutant with disruption in the cytochrome c maturation gene ccmA was unable to produce any cytochrome c and to grow on vanadate. This phenotype could be restored by complementation with the pEC86 plasmid expressing ccm genes from Escherichia coli. To our knowledge, this is the first report of E. coli ccm genes being functional in another organism. Analysis of an mtrB-deficient mutant confirmed the results of a previous paper indicating that OmcB may function as a vanadate reductase or may be part of a vanadate reductase complex.

scholarly journals Insight to Microbial Fe(III) Reduction Mediated by Redox-Active Humic Acids with Varied Redox Potentials

2021 ◽  
Vol 18 (13) ◽  
pp. 6807
Author(s):  
Jingtao Duan ◽  
Zhiyuan Xu ◽  
Zhen Yang ◽  
Jie Jiang
Keyword(s):  
Molecular Weight ◽  
Electron Transfer ◽  
Humic Acids ◽  
Weight Fraction ◽  
Electrochemical Analysis ◽  
Microbial Reduction ◽  
Redox Potentials ◽  
Groundwater Environment ◽  
Redox Active ◽  
Different Molecular Weight

Redox-active humic acids (HA) are ubiquitous in terrestrial and aquatic systems and are involved in numerous electron transfer reactions affecting biogeochemical processes and fates of pollutants in soil environments. Redox-active contaminants are trapped in soil micropores (<2 nm) that have limited access to microbes and HA. Therefore, the contaminants whose molecular structure and properties are not damaged accumulate in the soil micropores and become potential pollution sources. Electron transfer capacities (ETC) of HA reflecting redox activities of low molecular weight fraction (LMWF, <2.5) HA can be detected by an electrochemical method, which is related to redox potentials (Eh) in soil and aquatic environments. Nevertheless, electron accepting capacities (EAC) and electron donating capacities (EDC) of these LMWF HA at different Eh are still unknown. EDC and EAC of different molecular weight HA at different Eh were analyzed using electrochemical methods. EAC of LMWF at −0.59 V was 12 times higher than that at −0.49 V, while EAC increased to 2.6 times when the Eh decreased from −0.59 V to −0.69 V. Afterward, LMWF can act as a shuttle to stimulate microbial Fe(III) reduction processes in microbial reduction experiments. Additionally, EAC by electrochemical analysis at a range of −0.49–−0.59 V was comparable to total calculated ETC of different molecular weight fractions of HA by microbial reduction. Therefore, it is indicated that redox-active functional groups that can be reduced at Eh range of −0.49–−0.59 are available to microbial reduction. This finding contributes to a novel perspective in the protection and remediation of the groundwater environment in the biogeochemistry process.

scholarly journals Phytoplankton of the Curonian Lagoon as a New Interesting Source for Bioactive Natural Products. Special Impact on Cyanobacterial Metabolites

Biomolecules ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1139
Author(s):  
Donata Overlingė ◽  
Anna Toruńska-Sitarz ◽  
Marta Cegłowska ◽  
Agata Błaszczyk ◽  
Karolina Szubert ◽  
...  
Keyword(s):  
Natural Products ◽  
Serine Proteases ◽  
Ex Situ ◽  
Breast Adenocarcinoma ◽  
Curonian Lagoon ◽  
Bacterial Strains ◽  
Biotechnological Potential ◽  
Bioactive Natural Products ◽  
Field Samples ◽  
Sample Component

The bioprospecting of marine and brackish water systems has increased during the last decades. In this respect, microalgae, including cyanobacteria, and their metabolites are one of the most widely explored resources. Most of the bioactive compounds are isolated from ex situ cultures of microorganisms; however, analysis of field samples could also supply valuable information about the metabolic and biotechnological potential of microalgae communities. In this work, the activity of phytoplankton samples from the Curonian Lagoon was studied. The samples were active against antibiotic resistant clinical and environmental bacterial strains as well as against serine proteases and T47D human breast adenocarcinoma cells. No significant effect was found on Daphnia magna. In addition, using LC-MS/MS, we documented the diversity of metabolites present in field samples. A list of 117 detected cyanopeptides was presented. Cyanopeptolins constituted the largest class of cyanopeptides. As complex bloom samples were analyzed, no link between the observed activity and a specific sample component can be established. However, the results of the study showed a biotechnological potential of natural products from the Curonian Lagoon.

Ultrasound-Assisted Citric Acid Extraction of Zinc in Plateau Red Soil and Tessier Speciation Study

2013 ◽  
Vol 726-731 ◽  
pp. 4464-4467
Author(s):  
Wei Wei ◽  
Xue Jin Zhou ◽  
Yun Tao Gao
Keyword(s):  
Heavy Metal ◽  
Citric Acid ◽  
Manganese Oxides ◽  
Red Soil ◽  
Extraction Rate ◽  
Acid Extraction ◽  
Speciation Study ◽  
Ultrasonic Assisted ◽  
Ultrasound Assisted ◽  
Iron And Manganese

Taking plateau red soil as research object, using the ultrasonic-assisted organic acid extraction the heavy metal zinc in it, and analyze the form of zinc. Results showed that the extraction rate can reach 68%, with the increase of time, the extraction effect of zinc is obviously enhanced in this method. Ultrasonic-assisted citric acid extraction soil can increase the extraction rate of exchangeable, bound to carbonates and bound to iron and manganese oxides relatively.

Strategies for EELS Data Analysis. Introducing UMAP and HDBSCAN for Dimensionality Reduction and Clustering

2021 ◽  
pp. 1-14
Author(s):  
Javier Blanco-Portals ◽  
Francesca Peiró ◽  
Sònia Estradé
Keyword(s):  
Dimensionality Reduction ◽  
Clustering Analysis ◽  
Manganese Oxides ◽  
Spatial Clustering ◽  
State Of The Art ◽  
Core Loss ◽  
Nonnegative Matrix ◽  
Case Scenario ◽  
Electron Energy Loss ◽  
Iron And Manganese

Hierarchical density-based spatial clustering of applications with noise (HDBSCAN) and uniform manifold approximation and projection (UMAP), two new state-of-the-art algorithms for clustering analysis, and dimensionality reduction, respectively, are proposed for the segmentation of core-loss electron energy loss spectroscopy (EELS) spectrum images. The performances of UMAP and HDBSCAN are systematically compared to the other clustering analysis approaches used in EELS in the literature using a known synthetic dataset. Better results are found for these new approaches. Furthermore, UMAP and HDBSCAN are showcased in a real experimental dataset from a core–shell nanoparticle of iron and manganese oxides, as well as the triple combination nonnegative matrix factorization–UMAP–HDBSCAN. The results obtained indicate how the complementary use of different combinations may be beneficial in a real-case scenario to attain a complete picture, as different algorithms highlight different aspects of the dataset studied.

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