scholarly journals Iron Corrosion Induced by Nonhydrogenotrophic Nitrate-Reducing Prolixibacter sp. Strain MIC1-1

2014 ◽  
Vol 81 (5) ◽  
pp. 1839-1846 ◽  
Author(s):  
Takao Iino ◽  
Kimio Ito ◽  
Satoshi Wakai ◽  
Hirohito Tsurumaru ◽  
Moriya Ohkuma ◽  
...  
Keyword(s):  
Carbon Source ◽  
Electron Donor ◽  
Microbiologically Influenced Corrosion ◽  
Rrna Gene ◽  
Oil Well ◽  
Metallic Materials ◽  
Anaerobic Conditions ◽  
Iron Corrosion ◽  
Content Type ◽  
Donor Acceptor

ABSTRACTMicrobiologically influenced corrosion (MIC) of metallic materials imposes a heavy economic burden. The mechanism of MIC of metallic iron (Fe0) under anaerobic conditions is usually explained as the consumption of cathodic hydrogen by hydrogenotrophic microorganisms that accelerates anodic Fe0oxidation. In this study, we describe Fe0corrosion induced by a nonhydrogenotrophic nitrate-reducing bacterium called MIC1-1, which was isolated from a crude-oil sample collected at an oil well in Akita, Japan. This strain requires specific electron donor-acceptor combinations and an organic carbon source to grow. For example, the strain grew anaerobically on nitrate as a sole electron acceptor with pyruvate as a carbon source and Fe0as the sole electron donor. In addition, ferrous ion andl-cysteine served as electron donors, whereas molecular hydrogen did not. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain MIC1-1 was a member of the genusProlixibacterin the orderBacteroidales. Thus,Prolixibactersp. strain MIC1-1 is the first Fe0-corroding representative belonging to the phylumBacteroidetes. Under anaerobic conditions,Prolixibactersp. MIC1-1 corroded Fe0concomitantly with nitrate reduction, and the amount of iron dissolved by the strain was six times higher than that in an aseptic control. Scanning electron microscopy analyses revealed that microscopic crystals of FePO4developed on the surface of the Fe0foils, and a layer of FeCO3covered the FePO4crystals. We propose that cells ofProlixibactersp. MIC1-1 accept electrons directly from Fe0to reduce nitrate.

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.

Amphibacillus cookii sp. nov., a facultatively aerobic, spore-forming, moderately halophilic, alkalithermotolerant bacterium

2012 ◽  
Vol 62 (Pt_9) ◽  
pp. 2090-2096 ◽  
Author(s):  
Benoît Pugin ◽  
Jenny M. Blamey ◽  
Bonnie K. Baxter ◽  
Juergen Wiegel
Keyword(s):  
Type Species ◽  
Salt Lake ◽  
Sequence Similarity ◽  
Halophilic Bacteria ◽  
Rrna Gene ◽  
Anaerobic Conditions ◽  
Fermentation Products ◽  
Aerobic Conditions ◽  
Content Type ◽  
Link Type

Novel strains of facultatively aerobic, moderately alkaliphilic and facultatively halophilic bacteria were isolated from a sediment sample taken from the Southern Arm of Great Salt Lake, Utah. Cells of strain JW/BP-GSL-QDT (and related strains JW/BP-GSL-RA and JW/BP-GSL-WB) were rod-shaped, spore-forming, motile bacteria with variable Gram-staining. Strain JW/BP-GSL-QDT grew under aerobic conditions between 14.5 and 47 °C (optimum 39 °C), in the pH37 °C range 6.5–10.3 (optimum pH37 °C 8.0), and between 0.1 and 4.5 M Na+ (optimum 0.9 M Na+). No growth was observed in the absence of supplemented Na+. Strain JW/BP-GSL-QDT utilized l-arabinose, d-fructose, d-galactose, d-glucose, inulin, lactose, maltose, mannitol, d-mannose, pyruvate, d-ribose, d-sorbitol, starch, trehalose, xylitol and d-xylose under both aerobic and anaerobic conditions, and used ethanol and methanol only under aerobic conditions. Strains JW/BP-GSL-WB and JW/BP-GSL-RA had the same profiles except that methanol was not used aerobically. During growth on glucose, the major organic compounds formed under aerobic conditions were acetate and lactate, and under anaerobic conditions, the fermentation products were formate, acetate, lactate and ethanol. Oxidase and catalase activities were not detected and cytochrome was absent. No respiratory quinones were detected. The main cellular fatty acids were iso-C15 : 0 (39.1 %) and anteiso-C15 : 0 (36.3 %). Predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and an unknown phospholipid. Additionally, a small amount of an unknown glycolipid was detected. The DNA G+C content of strain JW/BP-GSL-QDT was 35.4 mol% (determined by HPLC). For strain JW/BP-GSL-QDT the highest degree of 16S rRNA gene sequence similarity was found with Amphibacillus jilinensis (98.6 %), Amphibacillus sediminis (96.7 %) and Amphibacillus tropicus (95.6 %). The level of DNA–DNA relatedness between strain JW/BP-GSL-QDT and A. jilinensis Y1T was 58 %. On the basis of physiological, chemotaxonomic and phylogenetic data, strain JW/BP-GSL-QDT represents a novel species of the genus Amphibacillus , for which the name Amphibacillus cookii sp. nov. is proposed. The type strain is JW/BP-GSL-QDT ( = ATCC BAA-2118T = DSM 23721T).

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 Microbial Community Analysis Provides Insights into the Effects of Tetrahydrofuran on 1,4-Dioxane Biodegradation

2019 ◽  
Vol 85 (11) ◽  
Author(s):  
Yi Xiong ◽  
Olivia U. Mason ◽  
Ashlee Lowe ◽  
Chao Zhou ◽  
Gang Chen ◽  
...  
Keyword(s):  
Microbial Community ◽  
Electron Donor ◽  
Landfill Leachate ◽  
Synthetic Medium ◽  
High Energy ◽  
Community Context ◽  
Rrna Gene ◽  
Content Type ◽  
Donor Substrate ◽  
Degrading Bacteria

ABSTRACTTetrahydrofuran (THF) is known to induce the biodegradation of 1,4-dioxane (dioxane), an emerging contaminant, but the mechanisms by which THF affects dioxane biodegradation in microbial communities are not well understood. To fill this knowledge gap, changes in the microbial community structure in microcosm experiments with synthetic medium and landfill leachate were examined over time using 16S rRNA gene amplicon sequencing and functional gene quantitative PCR assays. The overarching hypothesis being tested was that THF promoted dioxane biodegradation by increasing the abundance of dioxane-degrading bacteria in the consortium. The data revealed that in experiments with synthetic medium, the addition of THF significantly increased the abundance ofPseudonocardia, a genus with several representatives that can grow on both dioxane and THF, and ofRhodococcus ruber, a species that can use THF as the primary growth substrate while cometabolizing dioxane. However, in similar experiments with landfill leachate, onlyR. ruberwas significantly enriched. When the THF concentration was higher than the dioxane concentration, THF competitively inhibited dioxane degradation since dioxane degradation was negligible, while the dioxane-degrading bacteria and the corresponding THF/dioxane monooxygenase gene copies increased by a few orders of magnitude.IMPORTANCEWidespread in groundwater and carcinogenic to humans, 1,4-dioxane (dioxane) is attracting significant attention in recent years. Advanced oxidation processes can effectively remove dioxane but require high energy consumption and operation costs. Biological removal of dioxane is of particular interest due to the ability of some bacteria to mineralize dioxane at a low energy cost. Although dioxane is generally considered recalcitrant to biodegradation, more than 20 types of bacteria can degrade dioxane as the sole electron donor substrate or the secondary electron donor substrate. In the latter case, tetrahydrofuran (THF) is commonly studied as the primary electron donor substrate. Previous work has shown that THF promotes dioxane degradation at a low THF concentration but inhibits dioxane degradation at a high THF concentration. Our work expanded on the previous work by mechanically examining the effects of THF on dioxane degradation in a microbial community context.

scholarly journals Pyogranulomatous Pneumonia in Goats Caused by an Undescribed Porphyromonas Species, “Porphyromonas katsikii”

2014 ◽  
Vol 53 (3) ◽  
pp. 795-798 ◽  
Author(s):  
George Filioussis ◽  
Evanthia Petridou ◽  
Emmanouel Karavanis ◽  
Joachim Frey
Keyword(s):  
Agar Medium ◽  
Bacterial Species ◽  
Pcr Amplification ◽  
Rrna Gene ◽  
Undescribed Species ◽  
Acute Respiratory Disease ◽  
Anaerobic Conditions ◽  
Specific Primers ◽  
Content Type

A yet-undescribed bacterial species, tentatively named “Porphyromonaskatsikii,” was isolated from individuals of a small goat herd with pyogranulomatous pneumonia during an outbreak of acute respiratory disease. The isolated bacteria grew in the form of black-pigmented colonies after 14 days of incubation under anaerobic conditions at 37°C on a tryptic soy blood agar medium. The bacteria were identified as a yet-undescribedPorphyromonasspecies by determination of the nucleotide sequence of therrs16S rRNA gene, and this species was tentatively namedPorphyromonaskatsikii. PCR amplification with specific primers for this yet-undescribed species revealed the presence ofP. katsikiiin the lung tissue of all affected animals, while no PCR signals were evidenced from the lungs of healthy goats or from goats with pasteurellosis caused byMannheimia haemolytica. These data indicateP. katsikiias the causative agent of acute respiratory distress.P. katsikiiis phylogenetically related toPorphyromonassomeraeandPorphyromonas levii, which cause pathologies in humans and animals, respectively.P. katsikiiwas not detected by PCR from samples of the gingival pockets or of the faces of healthy goats.

scholarly journals Iron Corrosion via Direct Metal-Microbe Electron Transfer

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Hai-Yan Tang ◽  
Dawn E. Holmes ◽  
Toshiyuki Ueki ◽  
Paola A. Palacios ◽  
Derek R. Lovley
Keyword(s):  
Electron Transfer ◽  
Electron Donor ◽  
Environmental Concern ◽  
Direct Electron Transfer ◽  
Anaerobic Respiration ◽  
Electrical Contacts ◽  
Geobacter Sulfurreducens ◽  
Donor Strain ◽  
Iron Corrosion ◽  
Content Type

ABSTRACTThe concept that anaerobic microorganisms can directly accept electrons from Fe(0) has been controversial because direct metal-microbe electron transfer has previously only been indirectly inferred. Fe(0) oxidation was studied withGeobacter sulfurreducensstrain ACL, an autotrophic strain that was previously shown to grow with electrons derived from a graphite cathode as the sole electron donor. Strain ACL grew with Fe(0) as the sole electron donor and fumarate as the electron acceptor. However, it appeared that at least a portion of the electron transfer was via H2produced nonenzymatically from the oxidation of Fe(0) to Fe(II). H2, which accumulated in abiotic controls, was consumed during the growth of strain ACL, the cells were predominately planktonic, and genes for the uptake hydrogenase were highly expressed. Strain ACLHFwas constructed to prevent growth on H2or formate by deleting the genes for the uptake of hydrogenase and formate dehydrogenases from strain ACL. Strain ACLHFalso grew with Fe(0) as the sole electron donor, but H2accumulated in the culture, and cells heavily colonized Fe(0) surfaces with no visible planktonic growth. Transcriptomics suggested that the outer surfacec-type cytochromes OmcS and OmcZ were important during growth of strain ACLHFon Fe(0). Strain ACLHFdid not grow on Fe(0) if the gene for either of these cytochromes was deleted. The specific attachment of strain ACLHFto Fe(0), coupled with requirements for known extracellular electrical contacts, suggest that direct metal-microbe electron transfer is the most likely option for Fe(0) serving as an electron donor.IMPORTANCEThe anaerobic corrosion of iron structures is expensive to repair and can be a safety and environmental concern. It has been known for over 100 years that the presence of anaerobic respiratory microorganisms can accelerate iron corrosion. Multiple studies have suggested that there are sulfate reducers, methanogens, and acetogens that can directly accept electrons from Fe(0) to support sulfate or carbon dioxide reduction. However, all of the strains studied can also use H2as an electron donor for growth, which is known to be abiotically produced from Fe(0). Furthermore, no proteins definitely shown to function as extracellular electrical contacts with Fe(0) were identified. The studies described here demonstrate that direct electron transfer from Fe(0) can support anaerobic respiration. They also map out a simple genetic approach to the study of iron corrosion mechanisms in other microorganisms. A better understanding of how microorganisms promote iron corrosion is expected to lead to the development of strategies that can help reduce adverse impacts from this process.

Metal-Free Photoinduced Hydroalkylation Cascade Enabled by an Electron-Donor-Acceptor Complex

2020 ◽  
Author(s):  
José Tiago Menezes Correia ◽  
Gustavo Piva da Silva ◽  
Camila Menezes Kisukuri ◽  
Elias André ◽  
Bruno Pires ◽  
...  
Keyword(s):  
Electron Donor ◽  
Functional Group ◽  
Photoexcited Electron ◽  
One Pot ◽  
Quaternary Centers ◽  
Metal Free ◽  
Acceptor Complex ◽  
Catalyst Free ◽  
Donor Acceptor ◽  
Radical Cascade

A metal- and catalyst-free photoinduced radical cascade hydroalkylation of 1,7-enynes has been disclosed. The process is triggered by a SET event involving a photoexcited electron-donor-aceptor complex between NHPI ester and Hantzsch ester, which decomposes to afford a tertiary radical that is readily trapped by the enyne. <a>The method provides an operationally simple, robust and step-economical approach to the construction of diversely functionalized dihydroquinolinones bearing quaternary-centers. A sequential one-pot hydroalkylation-isomerization approach is also allowed giving access to a family of quinolinones. A wide substrate scope and high functional group tolerance was observed in both approaches</a>.

scholarly journals Phyllobacterium loti sp. nov. isolated from nodules of Lotus corniculatus

2014 ◽  
Vol 64 (Pt_3) ◽  
pp. 781-786 ◽  
Author(s):  
Maximo Sánchez ◽  
Martha-Helena Ramírez-Bahena ◽  
Alvaro Peix ◽  
María J. Lorite ◽  
Juan Sanjuán ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Sequence Similarity ◽  
Carbon Sources ◽  
Lotus Corniculatus ◽  
Culture Conditions ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type ◽  
The 16S Rrna Gene

Strain S658T was isolated from a Lotus corniculatus nodule in a soil sample obtained in Uruguay. Phylogenetic analysis of the 16S rRNA gene and atpD gene showed that this strain clustered within the genus Phyllobacterium . The closest related species was, in both cases, Phyllobacterium trifolii PETP02T with 99.8 % sequence similarity in the 16S rRNA gene and 96.1 % in the atpD gene. The 16S rRNA gene contains an insert at the beginning of the sequence that has no similarities with other inserts present in the same gene in described rhizobial species. Ubiquinone Q-10 was the only quinone detected. Strain S658T differed from its closest relatives through its growth in diverse culture conditions and in the assimilation of several carbon sources. It was not able to reproduce nodules in Lotus corniculatus. The results of DNA–DNA hybridization, phenotypic tests and fatty acid analyses confirmed that this strain should be classified as a representative of a novel species of the genus Phyllobacterium , for which the name Phyllobacterium loti sp. nov. is proposed. The type strain is S658T( = LMG 27289T = CECT 8230T).

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