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Iron reducing bacteria

Qiushi Li, Jihui Wang, Xuteng Xing, Wenbin Hu
The corrosion behavior of X65 steel was investigated in the seawater inoculated with sulfate reducing bacteria (SRB) under the aerobic environment by electrochemical impedance techniques and immersion tests. The corroded morphologies and the composition of the corrosion products were investigated. The variation of the solution parameters including the bacterium number, the pH value and the soluble iron concentration were also investigated. The results indicated that in the SRB-containing system, the impedance responses presented a depressed semi-circle in the initial period, which then turned into the blocked electrode characteristic during the later immersion...
March 11, 2018: Bioelectrochemistry
Xiang Li, Yong Huang, Heng-Wei Liu, Chuan Wu, Wei Bi, Yi Yuan, Xin Liu
In recent years, there have been a number of reports on the phenomenon in which ferric iron (Fe(III)) is reduced to ferrous iron [Fe(II)] in anaerobic environments, accompanied by simultaneous oxidation of ammonia to NO2 - , NO3 - , or N2. However, studies on the relevant reaction characteristics and mechanisms are rare. Recently, in research on the effect of Fe(III) on the activity of Anammox sludge, excess ammonia oxidization has also been found. Hence, in the present study, Fe(III) was used to serve as the electron acceptor instead of NO2 - , and the feasibility and characteristics of Anammox coupled to Fe(III) reduction (termed Feammox) were investigated...
February 2018: Journal of Environmental Sciences (China)
Serku Kang, Yul Roh
The objectives of this research were to study the microbial diversity of metal-reducing bacteria enriched from sedimentary rock collected from a CO2 repository candidate site and to examine the effect that the bicarbonate concentration had on the iron reduction and biomineralization by the cultures. The enriched metal-reducing bacteria (i.e., JG-3) consisted mostly of Exiguobacterium sp. and Shewanella sp., and the microbial reduction of akaganeite (β-FeOOH), an Fe(III) oxyhydroxide, was examined over 7 days of bacterial cultivation at 30 °C under different concentrations of bicarbonate (0~210 mM)...
February 1, 2018: Journal of Nanoscience and Nanotechnology
Yu-Ping Yang, Hong-Mei Zhang, Hai-Yan Yuan, Gui-Lan Duan, De-Cai Jin, Fang-Jie Zhao, Yong-Guan Zhu
Arsenic (As) contamination is a global problem. Straw incorporation is widely performed in As contaminated paddy fields. To understand how straw and straw biochar incorporation affect As transformation and translocation in the soil-microbe-rice system, a pot experiment was carried out with different dosages of rice straw and straw biochar application. Results showed that both straw biochar and straw application significantly increased As mobility. Straw biochar mobilized As mainly through increasing soil pH and DOM content...
February 9, 2018: Environmental Pollution
Huihui Fu, Lulu Liu, Ziyang Dong, Shupan Guo, Haichun Gao
Iron, a major protein cofactor, is essential for most organisms but can be toxic simultaneously. Iron homeostasis thus has to be effectively maintained under a range of iron regimes. This may be particularly true with Shewanella oneidensis, a representative of dissimilatory metal-reducing bacteria (DMRB) capable of respiring a variety of chemicals as electron acceptors (EAs), including iron ores. Although iron respiration and its regulation have been extensively studied in this bacterium, how iron homeostasis is maintained remains largely unknown...
February 2, 2018: Applied and Environmental Microbiology
Yong-Ze Lu, Liang Fu, Na Li, Jing Ding, Ya-Nan Bai, Petros Samaras, Raymond Jianxiong Zeng
Coupling of anaerobic ammonium oxidation (Anammox) with denitrifying anaerobic methane oxidation (DAMO) is a sustainable pathway for nitrogen removal and reducing methane emissions from wastewater treatment processes. However, studies on the competitive relation between Anammox bacteria and DAMO bacteria are limited. Here, we investigated the effects of variations in the contents of trace element iron on Anammox and DAMO microorganisms. The short-term results indicated that optimal concentrations of iron, which obviously stimulated the activity of Amammox bacteria, DAMO bacteria and DAMO archaea, were 80, 20, and 80 μM, respectively...
February 1, 2018: Chemosphere
Jingkai Zhao, Chunyan Zhang, Cheng Sun, Wei Li, Shihan Zhang, Sujing Li, Dongxiao Zhang
A biocathode with the function of Fe(III)EDTA and Fe(II)EDTA-NO reduction was applied in a microbial electrolysis cell coupled with chemical absorption for NO removal from flue gas. As the mediated electron transfer was excluded by the same electrochemical characterizations of the biocathodes before and after a 48 h continuous operation, the profiles of reduction experiments indicated that direct electron transfer was the main mechanism of Fe(III)EDTA reduction, while Fe(III)EDTA-NO was mainly reduced via Fe(II)-assisted autotrophic denitrification...
February 1, 2018: Bioresource Technology
Jung-Soo Lee, Yoonjee Chang, Eun-Sil Lee, Hong-Geon Song, Pahn-Shick Chang, Jaejoon Han
A nonferrous oxygen scavenger (NFOS) comprising activated carbon and sodium l-ascorbate was developed to enhance the preservative efficacy of raw meatloaves. To determine the optimum formulation of activated carbon and sodium l-ascorbate, NFOSs with varying ratios of components (1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, and 1:2, w/w) were prepared and their oxygen-scavenging volumes were measured over 4 d at 25 °C. Assays of oxygen-scavenging capacities indicated that the optimum NFOS formulation of activated carbon and sodium l-ascorbate was achieved at a ratio of 1:1...
February 7, 2018: Journal of Food Science
Vita Wonoputri, Cindy Gunawan, Sanly Liu, Nicolas Barraud, Lachlan H Yee, May Lim, Rose Amal
The work found that the electron-donating properties of ferrous ions (Fe2+) can be used for the conversion of nitrite (NO2-) into the biofilm-dispersing signal nitric oxide (NO) by a copper(II) complex (CuDTTCT) catalyst, a potentially applicable biofilm control technology for the water industries. The availability of Fe2+ varied depending on the characteristics of the aqueous systems (phosphate- and carbonate-containing nitrifying bacteria growth medium, NBGM and phosphate buffered saline, PBS at pH 6 to 8, to simulate conditions typically present in the water industries) and was found to affect the production of NO from nitrite by CuDTTCT (casted into PVC)...
January 30, 2018: Nitric Oxide: Biology and Chemistry
Xing Wang, Baiwen Ma, Yaohui Bai, Huachun Lan, Huijuan Liu, Jiuhui Qu
Coagulation plays an important role in alleviating membrane fouling, and a noticeable problem is the development of microorganisms after long-time operation, which gradually secrete extracellular polymeric substances (EPS). To date, few studies have paid attention to the behavior of microorganisms in drinking water treatment with ultrafiltration (UF) membranes. Herein, the membrane biofouling was investigated with different aluminum and iron salts. We found that Al2(SO4)3·18H2O performed better in reducing membrane fouling due to the slower growth rate of microorganisms...
January 2018: Journal of Environmental Sciences (China)
Hanzhi Shi, Qi Li, Wenli Chen, Peng Cai, Qiaoyun Huang
Copper contamination of soils is a global environmental problem. Soil components (organic matter, clay minerals, and microorganisms) and retention time can govern the adsorption, fixation, and distribution of copper. This study evaluated the interaction effects of soil components and aging on the distribution of exogenous copper. Three typical Chinese soils (Ultisol, Alfisol, and Histosol) were collected from Hunan, Henan, and Heilongjiang Provinces. Soils were incubated with rice straw (RS) and engineered bacteria (Pseudomonas putida X4/pIME) in the presence of exogenous copper for 12 months...
February 2, 2018: Environmental Science and Pollution Research International
Olumide A Odeyemi, Christopher M Burke, Christopher J S Bolch, Roger Stanley
Under the current commercial practice, live mussels only have 10days' shelf-life. Observed spoilage indices reduce consumers' acceptance, palatability and shelf-life of modified atmosphere packaged (MAP) live mussels. The aims of this study are to isolate specific spoilage bacteria from modified atmosphere packaged live mussels, evaluate isolates for microbial spoilage indices using qualitative methods and volatile metabolites production. Forty-six hydrogen sulphide producing bacteria were isolated and evaluated for trimethylamine n-oxide (TMAO) reduction, proteolytic and lipolytic activities and hydrogen sulphide production...
January 2018: Food Research International
Anushila Chatterjee, Mark R O'Brian
Under iron limitation, bacteria scavenge ferric (Fe3+ ) iron bound to siderophores or other chelates from the environment to fulfill their nutritional requirement. In gram-negative bacteria, the siderophore uptake system prototype consists of an outer membrane transporter, a periplasmic binding protein, and a cytoplasmic membrane transporter, each specific for a single ferric siderophore or siderophore family. Here, we show that spontaneous single gain-of-function missense mutations in outer membrane transporter genes of Bradyrhizobium japonicum were sufficient to confer on cells the ability to use synthetic or natural iron siderophores, suggesting that selectivity is limited primarily to the outer membrane and can be readily modified...
January 30, 2018: Molecular Microbiology
Brittany D Bennett, Kaitlyn E Redford, Jeffrey A Gralnick
Shewanella oneidensis strain MR-1 is a versatile bacterium capable of respiring extracellular, insoluble ferric oxide minerals under anaerobic conditions. The respiration of iron minerals results in the production of soluble ferrous ions, which at high concentrations are toxic to living organisms. It is not fully understood how Fe2+ is toxic to cells anaerobically; nor is it fully understood how S. oneidensis is able to resist high levels of Fe2+ Here we describe the results of a transposon-mutant screen and subsequent deletion of the genes clpX and clpP in S...
January 29, 2018: Journal of Bacteriology
Palash Kumar Manna, Rachel Nickel, Yaroslav Wroczynskyj, Vinith Yathindranath, Jie Li, Song Liu, James A Thliveris, Thomas Klonisch, Donald W Miller, Johan van Lierop
A facile one-pot method of synthesizing amine-functionalized non-spherical Fe3O4 nanoparticles in gram-scale quantities is presented using just a single source of iron (iron (II) chloride) and an amine (triethylamine). The amine not only reduces iron salt to Fe3O4, but also directs the morphology of the nanoparticles along with the temperature of the reaction and functionalizes them making it very economical. By modifying the surface further, these nanoparticles promises to have useful biomedical applications...
January 27, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Violaine Bonnefoy, Barry M Grail, D Barrie Johnson
The type strain of the mineral-oxidizing acidophilic bacterium Acidithiobacillus ferridurans was grown in liquid media containing elevated concentrations of sodium chloride with hydrogen as electron donor. While it became more tolerant to chloride, after about one year, the salt-stressed acidophile was found to have lost its ability to oxidize iron, though not sulfur or hydrogen. Detailed molecular examination revealed that this was due to an insertion sequence, ISAfd1, which belongs to the ISPepr1 subgroup of the IS4 family, having been inserted downstream of the two promoters PI and PII of the rus operon (which codes for the iron oxidation pathway in this acidophile), thereby preventing its transcription...
January 26, 2018: Applied and Environmental Microbiology
Fen Wan, Linggen Kong, Haichun Gao
It is well established that OxyR functions as a transcriptional activator of the peroxide stress response in bacteria, primarily based on studies on Escherichia coli. Recent investigations have revealed that OxyRs of some other bacteria can regulate gene expression through both repression and activation or repression only; however, the underlying mechanisms remain largely unknown. Here, we demonstrated in g-proteobacterium Shewanella oneidensis that regulation of OxyR on expression of major catalase gene katB in a dual-control manner through interaction with a single site in the promoter region...
January 24, 2018: Journal of Biological Chemistry
Lei Chen, Peng Zhang, Weitao Shang, Hongxia Zhang, Yuntao Li, Weiguo Zhang, Zhaojie Zhang, Fanghua Liu
Many electroactive microorganisms (EAMs) are known as dissimilatory iron-reducing bacteria (DIRB) which can access iron as an electron acceptor to transfer electrons during the process of respiration. Previous research has shown that magnetic susceptibility (χlf) could be used as an indicator of DIRB activities. However, the relationship between χlf and electroactivity of EAMs is still unclear. Here, we report that after sediments of the Sha River enriched with amorphous iron, the χlf of enrichment cultures increased dramatically...
January 10, 2018: Bioelectrochemistry
Mara R de Lima E Silva, Regiane C Correa, Isabel K Sakamoto, Maria B A Varesche
Recent papers have confirmed current environmental pollution and the continuous release of polychlorinated biphenyls (PCBs) despite the prohibition of its manufacture worldwide. As the dehalogenating microorganisms are able to remove halogens from various analogous compounds, the characterization of PCB metabolisms can improve the degradation of similar compounds. Thus, this study extensively evaluated the microbial community developed in methanogenic and iron-reducing reactors. The horizontal-flow anaerobic reactor (HAIB) with real waste of Aroclor (1 mL L-1) was fed with mineral medium, ethanol, and sodium formate...
January 17, 2018: Current Microbiology
Yanning Zheng, Derek F Harris, Zheng Yu, Yanfen Fu, Saroj Poudel, Rhesa N Ledbetter, Kathryn R Fixen, Zhi-Yong Yang, Eric S Boyd, Mary E Lidstrom, Lance C Seefeldt, Caroline S Harwood
Methane (CH4) is a potent greenhouse gas that is released from fossil fuels and is also produced by microbial activity, with at least one billion tonnes of CH4 being formed and consumed by microorganisms in a single year 1 . Complex methanogenesis pathways used by archaea are the main route for bioconversion of carbon dioxide (CO2) to CH4 in nature2-4. Here, we report that wild-type iron-iron (Fe-only) nitrogenase from the bacterium Rhodopseudomonas palustris reduces CO2 simultaneously with nitrogen gas (N2) and protons to yield CH4, ammonia (NH3) and hydrogen gas (H2) in a single enzymatic step...
January 15, 2018: Nature Microbiology
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