scholarly journals A NovelShewanellaIsolate Enhances Corrosion by Using Metallic Iron as the Electron Donor with Fumarate as the Electron Acceptor

2018 ◽  
Vol 84 (20) ◽  
Author(s):  
Jo Philips ◽  
Niels Van den Driessche ◽  
Kim De Paepe ◽  
Antonin Prévoteau ◽  
Jeffrey A. Gralnick ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Metallic Iron ◽  
Hydrogen Generation ◽  
Formation Rate ◽  
Fold Increase ◽  
Hydrogen Formation ◽  
Content Type ◽  
Reducing Properties

ABSTRACTThe involvement ofShewanellaspp. in biocorrosion is often attributed to their Fe(III)-reducing properties, but they could also affect corrosion by using metallic iron as an electron donor. Previously, we isolatedShewanellastrain 4t3-1-2LB from an acetogenic community enriched with Fe(0) as the sole electron donor. Here, we investigated its use of Fe(0) as an electron donor with fumarate as an electron acceptor and explored its corrosion-enhancing mechanism. Without Fe(0), strain 4t3-1-2LB fermented fumarate to succinate and CO2, as was shown by the reaction stoichiometry and pH. With Fe(0), strain 4t3-1-2LB completely reduced fumarate to succinate and increased the Fe(0) corrosion rate (7.0 ± 0.6)-fold in comparison to that of abiotic controls (based on the succinate-versus-abiotic hydrogen formation rate). Fumarate reduction by strain 4t3-1-2LB was, at least in part, supported by chemical hydrogen formation on Fe(0). Filter-sterilized spent medium increased the hydrogen generation rate only 1.5-fold, and thus extracellular hydrogenase enzymes appear to be insufficient to explain the enhanced corrosion rate. Electrochemical measurements suggested that strain 4t3-1-2LB did not excrete dissolved redox mediators. Exchanging the medium and scanning electron microscopy (SEM) imaging indicated that cells were attached to Fe(0). It is possible that strain 4t3-1-2LB used a direct mechanism to withdraw electrons from Fe(0) or favored chemical hydrogen formation on Fe(0) through maintaining low hydrogen concentrations. In coculture with anAcetobacteriumstrain, strain 4t3-1-2LB did not enhance acetogenesis from Fe(0). This work describes a strong corrosion enhancement by aShewanellastrain through its use of Fe(0) as an electron donor and provides insights into its corrosion-enhancing mechanism.IMPORTANCEShewanellaspp. are frequently found on corroded metal structures. Their role in microbial influenced corrosion has been attributed mainly to their Fe(III)-reducing properties and, therefore, has been studied with the addition of an electron donor (lactate).Shewanellaspp., however, can also use solid electron donors, such as cathodes and potentially Fe(0). In this work, we show that the electron acceptor fumarate supported the use of Fe(0) as the electron donor byShewanellastrain 4t3-1-2LB, which caused a (7.0 ± 0.6)-fold increase of the corrosion rate. The corrosion-enhancing mechanism likely involved cell surface-associated components in direct contact with the Fe(0) surface or maintenance of low hydrogen levels by attached cells, thereby favoring chemical hydrogen formation by Fe(0). This work sheds new light on the role ofShewanellaspp. in biocorrosion, while the insights into the corrosion-enhancing mechanism contribute to the understanding of extracellular electron uptake processes.

scholarly journals Geobacter soli sp. nov., a dissimilatory Fe(III)-reducing bacterium isolated from forest soil

2014 ◽  
Vol 64 (Pt_11) ◽  
pp. 3786-3791 ◽  
Author(s):  
Shungui Zhou ◽  
Guiqin Yang ◽  
Qin Lu ◽  
Min Wu
Keyword(s):  
Forest Soil ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Type Species ◽  
Geobacter Sulfurreducens ◽  
Phenotypic Characterization ◽  
Strictly Anaerobic ◽  
Content Type ◽  
Link Type ◽  
Physiological Tests

A novel Fe(III)-reducing bacterium, designated GSS01T, was isolated from a forest soil sample using a liquid medium containing acetate and ferrihydrite as electron donor and electron acceptor, respectively. Cells of strain GSS01T were strictly anaerobic, Gram-stain-negative, motile, non-spore-forming and slightly curved rod-shaped. Growth occurred at 16–40 °C and optimally at 30 °C. The DNA G+C content was 60.9 mol%. The major respiratory quinone was MK-8. The major fatty acids were C16 : 0, C18 : 0 and C16 : 1ω7c/C16 : 1ω6c. Strain GSS01T was able to grow with ferrihydrite, Fe(III) citrate, Mn(IV), sulfur, nitrate or anthraquinone-2,6-disulfonate, but not with fumarate, as sole electron acceptor when acetate was the sole electron donor. The isolate was able to utilize acetate, ethanol, glucose, lactate, butyrate, pyruvate, benzoate, benzaldehyde, m-cresol and phenol but not toluene, p-cresol, propionate, malate or succinate as sole electron donor when ferrihydrite was the sole electron acceptor. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain GSS01T was most closely related to Geobacter sulfurreducens PCAT (98.3 % sequence similarity) and exhibited low similarities (94.9–91.8 %) to the type strains of other species of the genus Geobacter . The DNA–DNA relatedness between strain GSS01T and G. sulfurreducens PCAT was 41.4±1.1 %. On the basis of phylogenetic analysis, phenotypic characterization and physiological tests, strain GSS01T is believed to represent a novel species of the genus Geobacter , and the name Geobacter soli sp. nov. is proposed. The type strain is GSS01T ( = KCTC 4545T = MCCC 1K00269T).

scholarly journals Dissimilatory Nitrate Reduction to Ammonium (DNRA) and Denitrification Pathways Are Leveraged by Cyclic AMP Receptor Protein (CRP) Paralogues Based on Electron Donor/Acceptor Limitation in Shewanella loihica PV-4

2020 ◽  
Vol 87 (2) ◽  
Author(s):  
Shuangyuan Liu ◽  
Jingcheng Dai ◽  
Hehong Wei ◽  
Shuyang Li ◽  
Pei Wang ◽  
...  
Keyword(s):  
Global Warming ◽  
Carbon Source ◽  
Cyclic Amp ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Nitrite Reductase ◽  
Nitrate Reduction ◽  
Receptor Protein ◽  
Content Type ◽  
Dissimilatory Nitrate Reduction

ABSTRACT Under anoxic conditions, many bacteria, including Shewanella loihica strain PV-4, could use nitrate as an electron acceptor for dissimilatory nitrate reduction to ammonium (DNRA) and/or denitrification. Previous and current studies have shown that DNRA is favored under higher ambient carbon-to-nitrogen (C/N) ratios, whereas denitrification is upregulated under lower C/N ratios, which is consistent with our bioenergetics calculations. Interestingly, computational analyses indicate that the common cyclic AMP receptor protein (designated CRP1) and its paralogue CRP2 might both be involved in the regulation of two competing dissimilatory nitrate reduction pathways, DNRA and denitrification, in S. loihica PV-4 and several other denitrifying Shewanella species. To explore the regulatory mechanism underlying the dissimilatory nitrate reduction (DNR) pathways, nitrate reduction of a series of in-frame deletion mutants was analyzed under different C/N ratios. Deletion of crp1 could accelerate the reduction of nitrite to NO under both low and high C/N ratios. CRP1 is not required for denitrification and actually suppresses production of NO and N2O gases. Deletion of either of the NO-forming nitrite reductase genes nirK or crp2 blocked production of NO gas. Furthermore, real-time PCR and electrophoretic mobility shift assays (EMSAs) demonstrated that the transcription levels of DNRA-relevant genes such as nap-β (napDABGH), nrfA, and cymA were upregulated by CRP1, while nirK transcription was dependent on CRP2. There are tradeoffs between the different physiological roles of nitrate/lactate, as nitrogen nutrient/carbon source and electron acceptor/donor and CRPs may leverage dissimilatory nitrate reduction pathways for maximizing energy yield and bacterial survival under ambient environmental conditions. IMPORTANCE Some microbes utilize different dissimilatory nitrate reduction (DNR) pathways, including DNR to ammonia (DNRA) and denitrification pathways, for anaerobic respiration in response to ambient carbon/nitrogen ratio changes. Large-scale industrial nitrogen fixation and fertilizer application raise the concern of emission of N2O, a stable gas with potent global warming potential, as consequence of microbial respiration, thereby aggravating global warming and climate change. However, little is known about the molecular mechanism underlying the choice of two competing DNR pathways. We demonstrate that the global regulator CRP1, which is widely encoded in bacteria, is required for DNRA in S. loihica PV-4 strain, while the CRP2 paralogue is required for transcription of the nitrite reductase gene nirK for denitrification. Sufficient carbon source lead to the predominance of DNRA, while carbon source/electron donor deficiency may result in an incomplete denitrification process, raising the concern of high levels of N2O emission from nitrate-rich and carbon source-poor waters and soils.

scholarly journals Concurrent Haloalkanoate Degradation and Chlorate Reduction by Pseudomonas chloritidismutans AW-1T

2017 ◽  
Vol 83 (12) ◽  
Author(s):  
Peng Peng ◽  
Ying Zheng ◽  
Jasper J. Koehorst ◽  
Peter J. Schaap ◽  
Alfons J. M. Stams ◽  
...  
Keyword(s):  
Electron Donor ◽  
Electron Acceptor ◽  
Inorganic Compounds ◽  
Environmental Pollutants ◽  
Amino Acid Sequences ◽  
Halogenated Compounds ◽  
Metabolic Potential ◽  
Haloacid Dehalogenase ◽  
Content Type ◽  
Donor And Acceptor

ABSTRACT Haloalkanoates are environmental pollutants that can be degraded aerobically by microorganisms producing hydrolytic dehalogenases. However, there is a lack of information about the anaerobic degradation of haloalkanoates. Genome analysis of Pseudomonas chloritidismutans AW-1T, a facultative anaerobic chlorate-reducing bacterium, showed the presence of two putative haloacid dehalogenase genes, the l-DEX gene and dehI, encoding an l-2-haloacid dehalogenase (l-DEX) and a halocarboxylic acid dehydrogenase (DehI), respectively. Hence, we studied the concurrent degradation of haloalkanoates and chlorate as a yet-unexplored trait of strain AW-1T. The deduced amino acid sequences of l-DEX and DehI revealed 33 to 37% and 26 to 86% identities with biochemically/structurally characterized l-DEX and the d- and dl-2-haloacid dehalogenase enzymes, respectively. Physiological experiments confirmed that strain AW-1T can grow on chloroacetate, bromoacetate, and both l- and d-α-halogenated propionates with chlorate as an electron acceptor. Interestingly, growth and haloalkanoate degradation were generally faster with chlorate as an electron acceptor than with oxygen as an electron acceptor. In line with this, analyses of l-DEX and DehI dehalogenase activities using cell-free extract (CFE) of strain AW-1T grown on dl-2-chloropropionate under chlorate-reducing conditions showed up to 3.5-fold higher dehalogenase activity than the CFE obtained from AW-1T cells grown on dl-2-chloropropionate under aerobic conditions. Reverse transcription-quantitative PCR showed that the l-DEX gene was expressed constitutively independently of the electron donor (haloalkanoates or acetate) or acceptor (chlorate or oxygen), whereas the expression of dehI was induced by haloalkanoates. Concurrent degradation of organic and inorganic halogenated compounds by strain AW-1T represents a unique metabolic capacity in a single bacterium, providing a new piece of the puzzle of the microbial halogen cycle. IMPORTANCE Halogenated organic and inorganic compounds are important environmental pollutants that have carcinogenic and genotoxic effects on both animals and humans. Previous research studied the degradation of organic and inorganic halogenated compounds separately but not concurrently. This study shows concurrent degradation of halogenated alkanoates and chlorate as an electron donor and acceptor, respectively, coupled to growth in a single bacterium, Pseudomonas chloritidismutans AW-1T. Hence, besides biogenesis of molecular oxygen from chlorate reduction enabling a distinctive placement of strain AW-1T between aerobic and anaerobic microorganisms, we can now add another unique metabolic potential of this bacterium to the roster. The degradation of different halogenated compounds under anoxic conditions by a single bacterium is also of interest for the natural halogen cycle in different aquatic and terrestrial ecosystems where ample natural production of halogenated compounds has been documented.

scholarly journals Isolation of Acetogenic Bacteria That Induce Biocorrosion by Utilizing Metallic Iron as the Sole Electron Donor

2014 ◽  
Vol 81 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Souichiro Kato ◽  
Isao Yumoto ◽  
Yoichi Kamagata
Keyword(s):  
Electron Donor ◽  
Metallic Iron ◽  
Methanogenic Archaea ◽  
Community Analysis ◽  
Microbiologically Influenced Corrosion ◽  
Microbial Community Analysis ◽  
Iron Corrosion ◽  
Content Type ◽  
Anoxic Conditions ◽  
Acetogenic Bacteria

ABSTRACTCorrosion of iron occurring under anoxic conditions, which is termed microbiologically influenced corrosion (MIC) or biocorrosion, is mostly caused by microbial activities. Microbial activity that enhances corrosion via uptake of electrons from metallic iron [Fe(0)] has been regarded as one of the major causative factors. In addition to sulfate-reducing bacteria and methanogenic archaea in marine environments, acetogenic bacteria in freshwater environments have recently been suggested to cause MIC under anoxic conditions. However, no microorganisms that perform acetogenesis-dependent MIC have been isolated or had their MIC-inducing mechanisms characterized. Here, we enriched and isolated acetogenic bacteria that induce iron corrosion by utilizing Fe(0) as the sole electron donor under freshwater, sulfate-free, and anoxic conditions. The enriched communities produced significantly larger amounts of Fe(II) than the abiotic controls and produced acetate coupled with Fe(0) oxidation prior to CH4production. Microbial community analysis revealed thatSporomusasp. andDesulfovibriosp. dominated in the enrichments. Strain GT1, which is closely related to the acetogenSporomusa sphaeroides, was eventually isolated from the enrichment. Strain GT1 grew acetogenetically with Fe(0) as the sole electron donor and enhanced iron corrosion, which is the first demonstration of MIC mediated by a pure culture of an acetogen. Other well-known acetogenic bacteria, includingSporomusa ovataandAcetobacteriumspp., did not grow well on Fe(0). These results indicate that very few species of acetogens have specific mechanisms to efficiently utilize cathodic electrons derived from Fe(0) oxidation and induce iron corrosion.

scholarly journals Shewanella spp. Use Acetate as an Electron Donor for Denitrification but Not Ferric Iron or Fumarate Reduction

2013 ◽  
Vol 79 (8) ◽  
pp. 2818-2822 ◽  
Author(s):  
Sukhwan Yoon ◽  
Robert A. Sanford ◽  
Frank E. Löffler
Keyword(s):  
Electron Donor ◽  
Electron Acceptor ◽  
Iron Reduction ◽  
Ferric Iron ◽  
Acetate Oxidation ◽  
Content Type ◽  
Anoxic Conditions ◽  
Fumarate Reduction

ABSTRACTLactate but not acetate oxidation was reported to support electron acceptor reduction byShewanellaspp. under anoxic conditions. We demonstrate that the denitrifiersShewanella loihicastrain PV-4 andShewanella denitrificansOS217 utilize acetate as an electron donor for denitrification but not for fumarate or ferric iron reduction.

scholarly journals Anaerobic Benzene Oxidation by Geobacter Species

2012 ◽  
Vol 78 (23) ◽  
pp. 8304-8310 ◽  
Author(s):  
Tian Zhang ◽  
Timothy S. Bain ◽  
Kelly P. Nevin ◽  
Melissa A. Barlett ◽  
Derek R. Lovley
Keyword(s):  
Electron Donor ◽  
Electron Acceptor ◽  
Model Organism ◽  
Benzene Oxidation ◽  
Geobacter Metallireducens ◽  
Contaminated Aquifer ◽  
Content Type ◽  
Benzene Degradation ◽  
Contaminated Aquifers ◽  
Genetically Manipulated

ABSTRACTThe abundance ofGeobacterspecies in contaminated aquifers in which benzene is anaerobically degraded has led to the suggestion that someGeobacterspecies might be capable of anaerobic benzene degradation, but this has never been documented. A strain ofGeobacter, designated strain Ben, was isolated from sediments from the Fe(III)-reducing zone of a petroleum-contaminated aquifer in which there was significant capacity for anaerobic benzene oxidation. Strain Ben grew in a medium with benzene as the sole electron donor and Fe(III) oxide as the sole electron acceptor. Furthermore, additional evaluation ofGeobacter metallireducensdemonstrated that it could also grow in benzene-Fe(III) medium. In both strain Ben andG. metallireducensthe stoichiometry of benzene metabolism and Fe(III) reduction was consistent with the oxidation of benzene to carbon dioxide with Fe(III) serving as the sole electron acceptor. With benzene as the electron donor, and Fe(III) oxide (strain Ben) or Fe(III) citrate (G. metallireducens) as the electron acceptor, the cell yields of strain Ben andG. metallireducenswere 3.2 × 109and 8.4 × 109cells/mmol of Fe(III) reduced, respectively. Strain Ben also oxidized benzene with anthraquinone-2,6-disulfonate (AQDS) as the sole electron acceptor with cell yields of 5.9 × 109cells/mmol of AQDS reduced. Strain Ben serves as model organism for the study of anaerobic benzene metabolism in petroleum-contaminated aquifers, andG. metallireducensis the first anaerobic benzene-degrading organism that can be genetically manipulated.

Preponderant role of pentafluorophenyl moieties for tuning the electronic properties of extended benzodifuran-azomethine derivatives

2021 ◽  
Author(s):  
Chady Moussallem ◽  
Magali Allain ◽  
Frédéric Gohier ◽  
Pierre Frere
Keyword(s):  
Electronic Properties ◽  
Electron Donor ◽  
Electron Acceptor

From a central 3,7-bis(perfluorophenyl)-BDF unit, the extension performed with electron acceptor perfluorophenyl groups and/or electron donor N,N-dimethylamino groups via an imine link leads to symmetrical AAA and DAD or dissymmetrical...

scholarly journals Lachnospiraceae and Bacteroidales Alternative Fecal Indicators Reveal Chronic Human Sewage Contamination in an Urban Harbor

2011 ◽  
Vol 77 (19) ◽  
pp. 6972-6981 ◽  
Author(s):  
Ryan J. Newton ◽  
Jessica L. VandeWalle ◽  
Mark A. Borchardt ◽  
Marc H. Gorelick ◽  
Sandra L. McLellan
Keyword(s):  
Sequence Analysis ◽  
Genetic Marker ◽  
Microbial Community Composition ◽  
Fold Increase ◽  
Fecal Pollution ◽  
Plate Count ◽  
Rrna Gene ◽  
Fecal Indicators ◽  
Fecal Indicator ◽  
Content Type

ABSTRACTThe complexity of fecal microbial communities and overlap among human and other animal sources have made it difficult to identify source-specific fecal indicator bacteria. However, the advent of next-generation sequencing technologies now provides increased sequencing power to resolve microbial community composition within and among environments. These data can be mined for information on source-specific phylotypes and/or assemblages of phylotypes (i.e., microbial signatures). We report the development of a new genetic marker for human fecal contamination identified through microbial pyrotag sequence analysis of the V6 region of the 16S rRNA gene. Sequence analysis of 37 sewage samples and comparison with database sequences revealed a human-associated phylotype within theLachnospiraceaefamily, which was closely related to the genusBlautia. This phylotype, termed Lachno2, was on average the second most abundant fecal bacterial phylotype in sewage influent samples from Milwaukee, WI. We developed a quantitative PCR (qPCR) assay for Lachno2 and used it along with the qPCR-based assays for humanBacteroidales(based on the HF183 genetic marker), totalBacteroidalesspp., and enterococci and the conventionalEscherichia coliand enterococci plate count assays to examine the prevalence of fecal and human fecal pollution in Milwaukee's harbor. Both the conventional fecal indicators and the human-associated indicators revealed chronic fecal pollution in the harbor, with significant increases following heavy rain events and combined sewer overflows. The two human-associated genetic marker abundances were tightly correlated in the harbor, a strong indication they target the same source (i.e., human sewage). Human adenoviruses were routinely detected under all conditions in the harbor, and the probability of their occurrence increased by 154% for every 10-fold increase in the human indicator concentration. Both Lachno2 and humanBacteroidalesincreased specificity to detect sewage compared to general indicators, and the relationship to a human pathogen group suggests that the use of these alternative indicators will improve assessments for human health risks in urban waters.

scholarly journals Role of Serum Mycoplasma pneumoniae IgA, IgM, and IgG in the Diagnosis of Mycoplasma pneumoniae-Related Pneumonia in School-Age Children and Adolescents

2016 ◽  
Vol 24 (1) ◽  
Author(s):  
Wei-Ju Lee ◽  
Eng-Yen Huang ◽  
Chih-Min Tsai ◽  
Kuang-Che Kuo ◽  
Yi-Chuan Huang ◽  
...  
Keyword(s):  
Children And Adolescents ◽  
Mycoplasma Pneumoniae ◽  
Immunoglobulin A ◽  
Fold Increase ◽  
Laboratory Diagnosis ◽  
Diagnostic Value ◽  
Immunoglobulin M ◽  
School Age Children ◽  
School Age ◽  
Content Type

ABSTRACT Mycoplasma pneumoniae is an important causative pathogen of community-acquired pneumonia in children. Rapid and reliable laboratory diagnosis of M. pneumoniae infection is important so that appropriate antibiotic treatment can be initiated to reduce the misuse of drugs and resistance rates. Anti-M. pneumoniae immunoglobulin M (IgM) is an indicator of recent primary infection but can persist for several months after initial infection. It has been suggested that anti-M. pneumoniae immunoglobulin A (IgA) can be a reliable indicator for recent M. pneumoniae infection in adults. We investigated the clinical diagnostic value of M. pneumoniae IgA in school-age children and adolescents with M. pneumoniae-related pneumonia. Eighty children with pneumonia and seropositive for M. pneumoniae IgM or with a 4-fold increase of anti-M. pneumoniae immunoglobulin G (IgG) were enrolled from May 2015 to March 2016. The titers of M. pneumoniae IgA, IgM, and IgG, the clinical features, and laboratory examinations of blood, C-reactive protein, and liver enzymes were analyzed. The initial positivity rates for M. pneumoniae IgM and IgA upon admission to the hospital were 63.6 and 33.8%, respectively. One week after admission, the cumulative positivity rates for M. pneumoniae IgM and IgA increased to 97.5 and 56.3%, respectively. Detection of M. pneumoniae IgM was more sensitive than detection of M. pneumoniae IgA for the diagnosis of M. pneumoniae-related pneumonia in school-age children and adolescents; however, paired sera are necessary for a more accurate diagnosis.

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