scholarly journals Pseudomonas moraviensis subsp. stanleyae, a bacterial endophyte of hyperaccumulator Stanleya pinnata , is capable of efficient selenite reduction to elemental selenium under aerobic conditions

2015 ◽  
Vol 119 (2) ◽  
pp. 400-410 ◽  
Author(s):  
L.C. Staicu ◽  
C.J. Ackerson ◽  
P. Cornelis ◽  
L. Ye ◽  
R.L. Berendsen ◽  
...  
Keyword(s):  
Elemental Selenium ◽  
Selenite Reduction ◽  
Aerobic Conditions ◽  
Bacterial Endophyte ◽  
Stanleya Pinnata

Reduction of Selenite and Detoxification of Elemental Selenium by the Phototrophic BacteriumRhodospirillum rubrum

1999 ◽  
Vol 65 (11) ◽  
pp. 4734-4740 ◽  
Author(s):  
J. Kessi ◽  
M. Ramuz ◽  
E. Wehrli ◽  
M. Spycher ◽  
R. Bachofen
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Cell Density ◽  
Culture Medium ◽  
Rhodospirillum Rubrum ◽  
Buoyant Density ◽  
Elemental Selenium ◽  
Selenite Reduction ◽  
Final Cell Density ◽  
Cell Densities

ABSTRACT The effect of selenite on growth kinetics, the ability of cultures to reduce selenite, and the mechanism of detoxification of selenium were investigated by using Rhodospirillum rubrum. Anoxic photosynthetic cultures were able to completely reduce as much as 1.5 mM selenite, whereas in aerobic cultures a 0.5 mM selenite concentration was only reduced to about 0.375 mM. The presence of selenite in the culture medium strongly affected cell division. In the presence of a selenite concentration of 1.5 mM cultures reached final cell densities that were only about 15% of the control final cell density. The cell density remained nearly constant during the stationary phase for all of the selenite concentrations tested, showing that the cells were not severely damaged by the presence of selenite or elemental selenium. Particles containing elemental selenium were observed in the cytoplasm, which led to an increase in the buoyant density of the cells. Interestingly, the change in the buoyant density was reversed after selenite reduction was complete; the buoyant density of the cells returned to the buoyant density of the control cells. This demonstrated that R. rubrum expels elemental selenium across the plasma membrane and the cell wall. Accordingly, electron-dense particles were more numerous in the cells during the reduction phase than after the reduction phase.

scholarly journals Delayed formation of zero-valent selenium nanoparticles by Bacillus mycoides SeITE01 as a consequence of selenite reduction under aerobic conditions

2014 ◽  
Vol 13 (1) ◽  
pp. 35 ◽  
Author(s):  
Silvia Lampis ◽  
Emanuele Zonaro ◽  
Cristina Bertolini ◽  
Paolo Bernardi ◽  
Clive S Butler ◽  
...  
Keyword(s):  
Selenium Nanoparticles ◽  
Bacillus Mycoides ◽  
Selenite Reduction ◽  
Aerobic Conditions

SELENITE REDUCTION BY SALMONELLA HEIDELBERG

1966 ◽  
Vol 12 (4) ◽  
pp. 703-714 ◽  
Author(s):  
R. G. L. McCready ◽  
J. N. Campbell ◽  
J. I. Payne
Keyword(s):  
Cell Division ◽  
Morphological Changes ◽  
Lag Phase ◽  
Elemental Selenium ◽  
Selenite Reduction ◽  
X Ray ◽  
Growth Studies ◽  
Salmonella Heidelberg ◽  
Selenite Toxicity

When Salmonella Heidelberg is grown in 0.1% w/v Na2SeO3 and examined microscopically during growth, two morphological changes can be seen. Red intracellular granules are seen in most of the population within 10 to 12 hours, and organisms containing granules elongate without cell division. The intracellular granules produced by S. heidelberg in selenite broth have been identified by X-ray analysis as amorphous red selenium. The intermediate in the conversion of selenite to elemental selenium has been trapped and identified as divalent selenium ion. Growth studies have shown that selenite toxicity is primarily associated with the lag phase of growth, and also that the divalent intermediate is more toxic than the tetravalent precursor.

scholarly journals Stenotrophomonas maltophilia SeITE02, a New Bacterial Strain Suitable for Bioremediation of Selenite-Contaminated Environmental Matrices

2007 ◽  
Vol 73 (21) ◽  
pp. 6854-6863 ◽  
Author(s):  
Paolo Antonioli ◽  
Silvia Lampis ◽  
Irene Chesini ◽  
Giovanni Vallini ◽  
Sara Rinalducci ◽  
...  
Keyword(s):  
Bacterial Strain ◽  
Stenotrophomonas Maltophilia ◽  
Maximum Activity ◽  
Mass Spectrometry Analysis ◽  
Elemental Selenium ◽  
Cellular Transport ◽  
Environmental Matrices ◽  
Nucleotide Synthesis ◽  
Selenite Reduction

ABSTRACT Biochemical and proteomic tools have been utilized for investigating the mechanism of action of a new Stenotrophomonas maltophilia strain (SeITE02), a gammaproteobacterium capable of resistance to high concentrations of selenite [SeO3 2−, Se(IV)], reducing it to nontoxic elemental selenium under aerobic conditions; this strain was previously isolated from a selenite-contaminated mining soil. Biochemical analysis demonstrated that (i) nitrite reductase does not seem to take part in the process of selenite reduction by the bacterial strain SeITE02, although its involvement in this process had been hypothesized in other cases; (ii) nitrite strongly interferes with selenite removal when the two oxyanions (NO2 − and SeO3 2−) are simultaneously present, suggesting that the two reduction/detoxification pathways share a common enzymatic step, probably at the level of cellular transport; (iii) in vitro, selenite reduction does not take place in the membrane or periplasmic fractions but only in the cytoplasm, where maximum activity is exhibited at pH 6.0 in the presence of NADPH; and (iv) glutathione is involved in the selenite reduction mechanism, since inhibition of its synthesis leads to a considerable delay in the onset of reduction. As far as the proteomic findings are concerned, the evidence was reached that 0.2 mM selenite and 16 mM nitrite, when added to the culture medium, caused a significant modulation (ca. 10%, i.e., 96 and 85 protein zones, respectively) of the total proteins visualized in the respective two-dimensional maps. These spots were identified by mass spectrometry analysis and were found to belong to the following functional classes: nucleotide synthesis and metabolism, damaged-protein catabolism, protein and amino acid metabolism, and carbohydrate metabolism along with DNA-related proteins and proteins involved in cell division, oxidative stress, and cell wall synthesis.

Rhizosphere-induced Selenium Precipitation for Possible Applications in Phytoremediation of Se Polluted Effluents

2005 ◽  
Vol 60 (3-4) ◽  
pp. 349-356 ◽  
Author(s):  
Giovanni Vallini ◽  
Simona Di Gregorio ◽  
Silvia Lampis
Keyword(s):  
Rhizosphere Soil ◽  
Axenic Culture ◽  
Defined Medium ◽  
Model System ◽  
Elemental Selenium ◽  
Bacterial Isolates ◽  
Selenite Reduction ◽  
Biochemical Analyses ◽  
Kinetics Of ◽  
Astragalus Bisulcatus

Abstract Two bacterial isolates were obtained in axenic culture from the rhizosphere soil of Astragalus bisulcatus, a legume able to hyperaccumulate selenium. Both strains resulted of particular interest for their high resistance to the toxic oxyanion SeO32- (selenite, SeIV). On the basis of molecular and biochemical analyses, these two isolates were attributed to the species Bacillus mycoides and Stenotrophomonas maltophilia, respectively. Their capability in axenic culture to precipitate the soluble, bioavailable and highly toxic selenium form selenite to insoluble and relatively non-toxic Se0 (elemental selenium) was evaluated in defined medium added with 0.2 or 0.5 mm SeIV. Both strains showed to completely reduce 0.2 mᴍ selenite in 120 h, while 0.5 mm SeIV was reduced up to 67% of the initial concentration by B. mycoides and to about 50% by S. maltophilia in 48 h. Together in a dual consortium, B. mycoides and S. maltophilia increased the kinetics of selenite reduction, thus improving the efficiency of the process. A model system for selenium rhizofiltration based on plant-rhizobacteria interactions has been proposed.

scholarly journals Untargeted Metabolomics Investigation on Selenite Reduction to Elemental Selenium by Bacillus mycoides SeITE01

2021 ◽  
Vol 12 ◽  
Author(s):  
Greta Baggio ◽  
Ryan A. Groves ◽  
Roberto Chignola ◽  
Elena Piacenza ◽  
Alessandro Presentato ◽  
...  
Keyword(s):  
Time Course ◽  
Membrane Lipids ◽  
Untargeted Metabolomics ◽  
Elemental Selenium ◽  
Growth Stages ◽  
Bacterial Cells ◽  
Bacillus Mycoides ◽  
Thiol Compounds ◽  
Selenite Reduction ◽  
Signaling Strategies

Bacillus mycoides SeITE01 is an environmental isolate that transforms the oxyanion selenite (SeO32−) into the less bioavailable elemental selenium (Se0) forming biogenic selenium nanoparticles (Bio-SeNPs). In the present study, the reduction of sodium selenite (Na2SeO3) by SeITE01 strain and the effect of SeO32− exposure on the bacterial cells was examined through untargeted metabolomics. A time-course approach was used to monitor both cell pellet and cell free spent medium (referred as intracellular and extracellular, respectively) metabolites in SeITE01 cells treated or not with SeO32−. The results show substantial biochemical changes in SeITE01 cells when exposed to SeO32−. The initial uptake of SeO32− by SeITE01 cells (3h after inoculation) shows both an increase in intracellular levels of 4-hydroxybenzoate and indole-3-acetic acid, and an extracellular accumulation of guanosine, which are metabolites involved in general stress response adapting strategies. Proactive and defensive mechanisms against SeO32− are observed between the end of lag (12h) and beginning of exponential (18h) phases. Glutathione and N-acetyl-L-cysteine are thiol compounds that would be mainly involved in Painter-type reaction for the reduction and detoxification of SeO32− to Se0. In these growth stages, thiol metabolites perform a dual role, both acting against the toxic and harmful presence of the oxyanion and as substrate or reducing sources to scavenge ROS production. Moreover, detection of the amino acids L-threonine and ornithine suggests changes in membrane lipids. Starting from stationary phase (24 and 48h), metabolites related to the formation and release of SeNPs in the extracellular environment begin to be observed. 5-hydroxyindole acetate, D-[+]-glucosamine, 4-methyl-2-oxo pentanoic acid, and ethanolamine phosphate may represent signaling strategies following SeNPs release from the cytoplasmic compartment, with consequent damage to SeITE01 cell membranes. This is also accompanied by intracellular accumulation of trans-4-hydroxyproline and L-proline, which likely represent osmoprotectant activity. The identification of these metabolites suggests the activation of signaling strategies that would protect the bacterial cells from SeO32− toxicity while it is converting into SeNPs.

scholarly journals Transcriptional Response of Selenopolypeptide Genes and Selenocysteine Biosynthesis Machinery Genes inEscherichia coliduring Selenite Reduction

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Antonia Y. Tetteh ◽  
Katherine H. Sun ◽  
Chiu-Yueh Hung ◽  
Farooqahmed S. Kittur ◽  
Gordon C. Ibeanu ◽  
...  
Keyword(s):  
Growth Response ◽  
Inhibitory Concentration ◽  
Molecular Level ◽  
Transcriptional Response ◽  
Reduction Process ◽  
Elemental Selenium ◽  
Bacterial Cells ◽  
Quantitative Real Time Pcr ◽  
Selenite Reduction ◽  
E Coli

Bacteria can reduce toxic selenite into less toxic, elemental selenium (Se0), but the mechanism on how bacterial cells reduce selenite at molecular level is still not clear. We usedEscherichia colistrain K12, a common bacterial strain, as a model to study its growth response to sodium selenite (Na2SeO3) treatment and then used quantitative real-time PCR (qRT-PCR) to quantify transcript levels of threeE. coliselenopolypeptide genes and a set of machinery genes for selenocysteine (SeCys) biosynthesis and incorporation into polypeptides, whose involvements in the selenite reduction are largely unknown. We determined that 5 mM Na2SeO3treatment inhibited growth by∼50% while 0.001 to 0.01 mM treatments stimulated cell growth by∼30%. Under 50% inhibitory or 30% stimulatory Na2SeO3concentration, selenopolypeptide genes (fdnG,fdoG, andfdhF) whose products require SeCys but not SeCys biosynthesis machinery genes were found to be induced ≥2-fold. In addition, one sulfur (S) metabolic geneiscSand two previously reported selenite-responsive genessodAandgutSwere also induced ≥2-fold under 50% inhibitory concentration. Our findings provide insight about the detoxification of selenite inE. colivia induction of these genes involved in the selenite reduction process.

scholarly journals Selenium Nanoparticle Synthesized by Proteus mirabilis YC801: An Efficacious Pathway for Selenite Biotransformation and Detoxification

2018 ◽  
Vol 19 (12) ◽  
pp. 3809 ◽  
Author(s):  
Yuting Wang ◽  
Xian Shu ◽  
Jinyan Hou ◽  
Weili Lu ◽  
Weiwei Zhao ◽  
...  
Keyword(s):  
Proteus Mirabilis ◽  
Thioredoxin Reductase ◽  
Hydrodynamic Diameter ◽  
Elemental Selenium ◽  
Selenite Reduction ◽  
Reduction Activity ◽  
Selenium Nanoparticle ◽  
Infrared Spectral ◽  
Average Hydrodynamic Diameter

Selenite is extremely biotoxic, and as a result of this, exploitation of microorganisms able to reduce selenite to non-toxic elemental selenium (Se0) has attracted great interest. In this study, a bacterial strain exhibiting extreme tolerance to selenite (up to 100 mM) was isolated from the gut of adult Monochamus alternatus and identified as Proteus mirabilis YC801. This strain demonstrated efficient transformation of selenite into red selenium nanoparticles (SeNPs) by reducing nearly 100% of 1.0 and 5.0 mM selenite within 42 and 48 h, respectively. Electron microscopy and energy dispersive X-ray analysis demonstrated that the SeNPs were spherical and primarily localized extracellularly, with an average hydrodynamic diameter of 178.3 ± 11.5 nm. In vitro selenite reduction activity assays and real-time PCR indicated that thioredoxin reductase and similar proteins present in the cytoplasm were likely to be involved in selenite reduction, and that NADPH or NADH served as electron donors. Finally, Fourier-transform infrared spectral analysis confirmed the presence of protein and lipid residues on the surfaces of SeNPs. This is the first report on the capability of P. mirabilis to reduce selenite to SeNPs. P. mirabilis YC801 might provide an eco-friendly approach to bioremediate selenium-contaminated soil/water, as well as a bacterial catalyst for the biogenesis of SeNPs.

Insights into selenite reduction and biogenesis of elemental selenium nanoparticles by two environmental isolates of Burkholderia fungorum

2017 ◽  
Vol 34 ◽  
pp. 1-11 ◽  
Author(s):  
Nazanin Seyed Khoei ◽  
Silvia Lampis ◽  
Emanuele Zonaro ◽  
Kim Yrjälä ◽  
Paolo Bernardi ◽  
...  
Keyword(s):  
Selenium Nanoparticles ◽  
Elemental Selenium ◽  
Environmental Isolates ◽  
Selenite Reduction
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