scholarly journals X-Ray Absorption Near-Edge Structure (XANES) Spectroscopy Study of the Interaction of Silver Ions with Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli

2013 ◽  
Vol 79 (20) ◽  
pp. 6385-6390 ◽  
Author(s):  
Gudrun Lisa Bovenkamp ◽  
Ulrike Zanzen ◽  
Katla Sai Krishna ◽  
Josef Hormes ◽  
Alexander Prange
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Silver Ions ◽  
Xanes Spectroscopy ◽  
Gram Positive ◽  
Edge Structure ◽  
Content Type ◽  
X Ray ◽  
X Ray Absorption

ABSTRACTSilver ions are widely used as antibacterial agents, but the basic molecular mechanism of this effect is still poorly understood. X-ray absorption near-edge structure (XANES) spectroscopy at the AgLIII, SK, and PKedges reveals the chemical forms of silver inStaphylococcus aureusandEscherichia coli(Ag+treated). The AgLIII-edge XANES spectra of the bacteria are all slightly different and very different from the spectra of silver ions (silver nitrate and silver acetate), which confirms that a reaction occurs. Death or inactivation of bacteria was observed by plate counting and light microscopy. Silver bonding to sulfhydryl groups (Ag-S) in cysteine and Ag-N or Ag-O bonding in histidine, alanine, anddl-aspartic acid was detected by using synthesized silver-amino acids. Significantly lower silver-cysteine content, coupled with higher silver-histidine content, in Gram-positiveS. aureusandListeria monocytogenescells indicates that the peptidoglycan multilayer could be buffering the biocidal effect of silver on Gram-positive bacteria, at least in part. Bonding of silver to phosphate groups was not detected. Interaction with DNA or proteins can occur through Ag-N bonding. The formation of silver-cysteine can be confirmed for both bacterial cell types, which supports the hypothesis that enzyme-catalyzed reactions and the electron transport chain within the cell are disrupted.

scholarly journals Screening of Escherichia coli Species Biodiversity Reveals New Biofilm-Associated Antiadhesion Polysaccharides

mBio ◽  
2011 ◽  
Vol 2 (3) ◽  
Author(s):  
Olaya Rendueles ◽  
Laetitia Travier ◽  
Patricia Latour-Lambert ◽  
Thierry Fontaine ◽  
Julie Magnus ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Bacterial Adhesion ◽  
Bioactive Molecules ◽  
Bacterial Biofilms ◽  
Gram Positive ◽  
Content Type ◽  
E Coli ◽  
Species Biodiversity

ABSTRACTBacterial biofilms often form multispecies communities in which complex but ill-understood competition and cooperation interactions occur. In light of the profound physiological modifications associated with this lifestyle, we hypothesized that the biofilm environment might represent an untapped source of natural bioactive molecules interfering with bacterial adhesion or biofilm formation. We produced cell-free solutions extracted fromin vitromature biofilms formed by 122 naturalEscherichia coliisolates, and we screened these biofilm extracts for antiadhesion molecules active on a panel of Gram-positive and Gram-negative bacteria. Using this approach, we showed that 20% of the tested biofilm extracts contained molecules that antagonize bacterial growth or adhesion. We characterized a compound, produced by a commensal animalE. colistrain, for which activity is detected only in biofilm extract. Biochemical and genetic analyses showed that this compound corresponds to a new type of released high-molecular-weight polysaccharide whose biofilm-associated production is regulated by the RfaH protein. We demonstrated that the antiadhesion activity of this polysaccharide was restricted to Gram-positive bacteria and that its production reduced susceptibility to invasion and provided rapid exclusion ofStaphylococcus aureusfrom mixedE. coliandS. aureusbiofilms. Our results therefore demonstrate that biofilms contain molecules that contribute to the dynamics of mixed bacterial communities and that are not or only poorly detected in unconcentrated planktonic supernatants. Systematic identification of these compounds could lead to strategies that limit pathogen surface colonization and reduce the burden associated with the development of bacterial biofilms on medical devices.IMPORTANCEWe sought to demonstrate that bacterial biofilms are reservoirs for unknown molecules that antagonize bacterial adhesion. The use of natural strains representative ofEscherichia colispecies biodiversity showed that nonbiocidal antiadhesion polysaccharides are frequently found in mature biofilm extracts (bacterium-free suspensions which contain soluble molecules produced within the biofilm). Release of an antiadhesion polysaccharide confers a competitive advantage upon the producing strain against clinically relevant pathogens such asStaphylococcus aureus. Hence, exploring the biofilm environment provides a better understanding of bacterial interactions within complex communities and could lead to improved control of pathogen colonization.

scholarly journals Performance of secondary P-fertilizers in pot experiments analyzed by phosphorus X-ray absorption near-edge structure (XANES) spectroscopy

AMBIO ◽  
2017 ◽  
Vol 47 (S1) ◽  
pp. 62-72 ◽  
Author(s):  
Christian Vogel ◽  
Camille Rivard ◽  
Verena Wilken ◽  
Andreas Muskolus ◽  
Christian Adam
Keyword(s):  
Xanes Spectroscopy ◽  
Edge Structure ◽  
X Ray ◽  
Pot Experiments ◽  
X Ray Absorption ◽  
P Fertilizers

Phosphorus K-edge XANES spectroscopy has probably often underestimated iron oxyhydroxide-bound P in soils

2018 ◽  
Vol 25 (6) ◽  
pp. 1736-1744 ◽  
Author(s):  
Jörg Prietzel ◽  
Wantana Klysubun
Keyword(s):  
Linear Combination ◽  
Xanes Spectroscopy ◽  
Organic P ◽  
Iron Oxyhydroxide ◽  
Edge Structure ◽  
X Ray ◽  
Soil P ◽  
P Sorption ◽  
Fe Oxyhydroxides ◽  
X Ray Absorption

Phosphorus (P) K-edge X-ray absorption near-edge structure (XANES) spectra of orthophosphate (oPO4) bound to soil FeIII minerals (e.g. ferrihydrite, goethite) show a pre-edge signal at 2148–2152 eV. It is unknown whether organic P bound to FeIII oxyhydroxides also show this feature. Otherwise, Fe-bound soil P may be underestimated by P K-edge XANES spectroscopy, because a large portion of Fe oxyhydroxide-bound P in soils is organic P. K-edge XANES spectra were obtained for different organic P compounds present in soils [inositol hexaphosphate (IHP), glucose-6-phosphate (G6P), adenosine triphosphate (ATP)] after sorption to ferrihydrite or goethite and compared with spectra of oPO4 adsorbed to these minerals. P sorption to ferrihydrite increased in the sequence IHP ≪ G6P < oPO4 < ATP. P sorption to goethite increased in the sequence G6P < oPO4 ≪ ATP = IHP. Pre-edge signals in P K-edge XANES spectra of organic P adsorbed to Fe oxyhydroxides were markedly smaller compared with those of oPO4 adsorbed to these minerals and absent for FeIII oxyhydroxide-bound ATP as well as goethite-bound IHP. Linear combination fitting (LCF) performed on spectra of IHP, G6P or ATP adsorbed to ferrihydrite or goethite, using only spectra of FeIII oxyhydroxide-bound oPO4 as reference compounds for Fe-bound P, erroneously assigned >93% (ferrihydrite) or >41% (goethite) of Fe-bound P to non-Fe-bound P species. Inclusion of FeIII oxyhydroxide-bound IHP as reference compounds markedly increased the recovery of oxyhydroxide-bound organic P. Thus, Fe-bound soil P has probably often been underestimated by LCF in soil XANES studies where IHP adsorbed to ferrihydrite and to goethite were not included as reference compounds.

Using X-ray absorption near edge structure (XANES) spectroscopy to determine selenium oxidation states in animal mineral supplements and feeds

2004 ◽  
Vol 84 (2) ◽  
pp. 171-175 ◽  
Author(s):  
C. R. Christensen ◽  
J. N. Cutler ◽  
D. A. Christensen
Keyword(s):  
Oxidation State ◽  
Animal Feed ◽  
Xanes Spectroscopy ◽  
Elemental Selenium ◽  
Selenium Speciation ◽  
Edge Structure ◽  
X Ray ◽  
Mineral Supplements ◽  
Animal Feeds ◽  
X Ray Absorption

Synchrotron-based X-ray absorption near edge structure (XANES) spectroscopy is a relatively new technique within the life sciences. XANES has been utilized to identify the location, oxidation state and spatial distribution of heavy metal elements in plants , neurons, blood and DNA, but has not been widely used in the animal sciences. Selenium content in animal feeds is monitored, as both selenium deficiencies and toxicities are associated with physiological disorders. Selenium is available as an animal feed in both inorganic and organic states. The bioavailability of selenium species has been tested in numerous animal trials; however, a simple, non-destructive test for selenium speciation is not available. The objective of this study was to determine whether XANES spectroscopy could be used to determine the selenium oxidation state found in various commercial animal feed products. A comparison of absorption spectra indicated that the animal mineral supplements contained an organoselenium or selenite. The processed animal feeds had a spectral profile similar to that of elemental selenium. Further experiments are necessary to determine the implication of selenium speciation on animal physiology. Key words: Selenium speciation, mineral supplements, ruminants, non-ruminants, synchrotron, XANES, X-ray

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