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Iron reducing bacteria

Manfred Nairz, Stefanie Dichtl, Andrea Schroll, David Haschka, Piotr Tymoszuk, Igor Theurl, Günter Weiss
The acute-phase response is triggered by the presence of infectious agents and danger signals which indicate hazards for the integrity of the mammalian body. One central feature of this response is the sequestration of iron into storage compartments including macrophages. This limits the availability of this essential nutrient for circulating pathogens, a host defence strategy known as 'nutritional immunity'. Iron metabolism and the immune response are intimately linked. In infections, the availability of iron affects both the efficacy of antimicrobial immune pathways and pathogen proliferation...
July 2018: Journal of Trace Elements in Medicine and Biology
Clement Chan, Vahid F Andisi, Dixon Ng, Nick Ostan, Warren K Yunker, Anthony B Schryvers
A number of important Gram-negative pathogens that reside exclusively in the upper respiratory or genitourinary tract of their mammalian host rely on surface receptors that specifically bind host transferrin and lactoferrin as a source of iron for growth. The transferrin receptors have been targeted for vaccine development due to their critical role in acquiring iron during invasive infection and for survival on the mucosal surface. In this study, we focus on the lactoferrin receptors, determining their prevalence in pathogenic bacteria and comparing their prevalence in commensal Neisseria to other surface antigens targeted for vaccines; addressing the issue of a reservoir for vaccine escape and impact of vaccination on the microbiome...
May 16, 2018: Biometals: An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine
Anne K Dunn
Alternative oxidase (Aox) is a non-energy conserving respiratory oxidase found in certain eukaryotes and bacteria, whose role in physiology is not entirely clear. Using the genetically tractable bacterium Vibrio fischeri as a model organism, we have identified a role for Aox to reduce levels of stress in cells exposed to oxygen and nitric oxide (NO). In V. fischeri lacking the NO-detoxifying enzyme flavohemoglobin (Hmp), deletion of aox in cells grown in the presence of oxygen and NO results in alterations to the transcriptome that include increases in transcripts mapping to stress-related genes...
May 14, 2018: Journal of Bacteriology
Sebastian Haas, Dirk de Beer, Judith M Klatt, Artur Fink, Rebecca McCauley Rench, Trinity L Hamilton, Volker Meyer, Brian Kakuk, Jennifer L Macalady
We report extremely low-light-adapted anoxygenic photosynthesis in a thick microbial mat in Magical Blue Hole, Abaco Island, The Bahamas. Sulfur cycling was reduced by iron oxides and organic carbon limitation. The mat grows below the halocline/oxycline at 30 m depth on the walls of the flooded sinkhole. In situ irradiance at the mat surface on a sunny December day was between 0.021 and 0.084 μmol photons m-2 s-1 , and UV light (<400 nm) was the most abundant part of the spectrum followed by green wavelengths (475-530 nm)...
2018: Frontiers in Microbiology
John M C Gutteridge, Barry Halliwell
The first life forms evolved in a highly reducing environment. This reduced state is still carried by cells today, which makes the concept of "reductive stress" somewhat redundant. When oxygen became abundant on the Earth, due to the evolution of photosynthesis, life forms had to adapt or become extinct. Living organisms did adapt, proliferated and an explosion of new life forms resulted, using reactive oxygen species (ROS) to drive their evolution. Adaptation to oxygen and its reduction intermediates necessitated the simultaneous evolution of select antioxidant defences, carefully regulated to allow ROS to perform their major roles...
May 9, 2018: Biochemical and Biophysical Research Communications
Kalline L Ribeiro, Isaac A M Frías, Octavio L Franco, Simoni C Dias, Ailton A Sousa-Junior, Osmar N Silva, Andris F Bakuzis, Maria D L Oliveira, Cesar A S Andrade
The use of central venous catheters (CVC) is highly associated with nosocomial blood infections and its use largely requires a systematic assessment of benefits and risks. Bacterial contamination of these tubes is frequent and may result in development of microbial consortia also known as biofilm. The woven nature of biofilm provides a practical defense against antimicrobial agents, facilitating bacterial dissemination through the patient's body and development of antimicrobial resistance. In this work, the authors describe the modification of CVC tubing by immobilizing Fe3 O4 -aminosilane core-shell nanoparticles functionalized with antimicrobial peptide clavanin A (clavA) as an antimicrobial prophylactic towards Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae...
April 27, 2018: Colloids and Surfaces. B, Biointerfaces
Qianru Xu, Wei Pan, Ranran Zhang, Qi Lu, Wanlei Xue, Cainan Wu, Bixiu Song, Shaoting Du
Cadmium (Cd) contamination of agricultural soils represents a serious risk to crop safety. A new strategy using abscisic acid (ABA)-generating bacteria, Bacillus subtilis or Azospirillum brasilense, was developed to reduce the Cd accumulation in plants grown in Cd-contaminated soil. Inoculation with either bacterium resulted in a pronounced increase in the ABA level in wild-type Arabidopsis Col-0 plants, accompanied by a decrease in Cd levels in plant tissues, which mitigated the Cd toxicity. As a consequence, the growth of plants exposed to Cd was improved...
May 8, 2018: Journal of Agricultural and Food Chemistry
Christopher R Doyle, Jee-Young Moon, Johanna P Daily, Tao Wang, Liise-Anne Pirofski
Pneumococcal conjugate vaccines (PCV) elicit opsonophagocytic (opsonic) antibodies to pneumococcal capsular polysaccharides (PPS) and reduce nasopharyngeal (NP) colonization by vaccine-included Streptococcus pneumoniae serotypes. However, non-opsonic antibodies may also be important for protection against pneumococcal disease. For example, 1E2, a mouse IgG1 monoclonal antibody (mAb) to the serotype 3 (ST3) PPS reduced ST3 NP colonization in mice and altered ST3 gene expression in vitro Here, we determined whether 1E2 affects ST3 gene expression in vivo during colonization of mice by performing RNA-seq on NP lavage fluid from ST3-infected mice treated with 1E2, a control mAb, or PBS...
May 7, 2018: Infection and Immunity
Yamin Deng, Tianliang Zheng, Yanxin Wang, Lun Liu, Hongchen Jiang, Teng Ma
Significant seasonal variation of groundwater arsenic (As) concentrations in shallow aquifers of the Jianghan Plain, central Yangtze River Basin has been reported recently, but the underlying mechanisms remain not well understood. To elaborate biogeochemical processes responsible for the observed As concentration variation, 42-day incubation experiments were done using sediment samples collected respectively from the depth of 26, 36 and 60m of the As-affected aquifer which were labeled respectively as JH26, JH36, JH60...
April 1, 2018: Science of the Total Environment
Man-Young Jung, So-Jeong Kim, Jong-Geol Kim, Heeji Hong, Joo-Han Gwak, Soo-Je Park, Yang-Hoon Kim, Sung-Keun Rhee
Members of the family Clostridiaceae within phylum Firmicutes are ubiquitous in various iron-reducing environments. However, genomic data on iron-reducing bacteria of the family Clostridiaceae, particularly regarding their environmental distribution, are limited. Here, we report the analysis and comparison of the genomic properties of Geosporobacter ferrireducens IRF9, a strict anaerobe that ferments sugars and degrades toluene under iron-reducing conditions, with those of the closely related species, Geosporobacter subterraneus DSM 17957...
May 2018: Journal of Microbiology / the Microbiological Society of Korea
Yu Han, Kun Zang, Changshui Liu, Yingjie Li, Qingjun Ma
Siderophore-interacting proteins (SIPs) play an important role in iron acquisition in many bacteria. SIPs release iron from the internalized ferric siderophore complex by reducing ferric iron to ferrous iron, but how the iron is reduced is not well understood. Here, a sip gene was identified in the genome of Vibrio anguillarum 775. To further understand the catalytic mechanism of the protein, the SIP was overexpressed in Escherichia coli Rosetta (DE3) cells, purified and crystallized for X-ray diffraction analysis...
May 1, 2018: Acta Crystallographica. Section F, Structural Biology Communications
Julia M Otte, Johannes Harter, Katja Laufer, Nia Blackwell, Daniel Straub, Andreas Kappler, Sara Kleindienst
Microaerophilic, phototrophic, and nitrate-reducing Fe(II)-oxidizers co-exist in coastal marine and littoral freshwater sediments. However, the in situ abundance, distribution, and diversity of metabolically active Fe(II)-oxidizers remained largely unexplored. Here, we characterized the microbial community composition at the oxic-anoxic interface of littoral freshwater (Lake Constance, Germany) and coastal marine sediments (Kalø Vig and Norsminde Fjord, Denmark) using DNA-/RNA-based next-generation 16S rRNA (gene) amplicon sequencing...
April 30, 2018: Environmental Microbiology
Zhengwen Zhang, Yuxing Han, Chunyan Xu, Wencheng Ma, Hongjun Han, Mengqi Zheng, Hao Zhu, Weiwei Ma
Mixotrophic denitrification coupled biological denitrification with iron and carbon micro-electrolysis (IC-ME) is a promising emerging bioprocess for nitrate removal of biologically enhanced treated coal gasification wastewater (BECGW) with low COD to nitrate ratio. TN removal efficiency in R1 with IC-ME assisted was 16.64% higher than R2 with scrap zero valent iron addition, 23.05% higher than R3 with active carbon assisted, 30.51% higher than R4 with only active sludge addition, 80.85% higher than R5 utilizing single IC-ME as control...
April 21, 2018: Bioresource Technology
Michelle M Valkanas, Nancy J Trun
A passive remediation system that treats coalmine drainage was sampled to determine the impact seasonal changes had on water quality and microbial diversity. Every quarter for 1 year, water-soil slurries were collected at the influent of the 5 settling ponds and the wetlands, and the effluent of the system. The concentration of 12 metals and sulfate, as well as sequences from the V4 region of the bacterial 16S rrn genes were determined. The water quality analysis revealed high levels of iron and sulfate, and measurable levels of Al, Ba, Cu, Pb, Mn, Sr, and Zn...
April 25, 2018: MicrobiologyOpen
Sheo Shankar Pandey, Pradeep Kumar Patnana, Yasobanta Padhi, Subhadeep Chatterjee
Expression of hrp (hypersensitive reaction and pathogenicity) genes inside the host is crucial for virulence of phytopathogenic bacteria. The hrp genes encode components of type3 secretion system (T3SS), HR elicitors and several regulators, which are involved in the co-ordinated expression of hrp genes in the host environment and in hrp inducing chemically defined medium. However, little is known about specific host or environmental factors which may play a role in the induction of hrp gene expression. In this study, we show that iron-limiting condition elicits induced expression of hrp genes, including type3 secretion system (T3SS) and effectors (T3E)...
April 24, 2018: Environmental Microbiology Reports
James Jamieson, Henning Prommer, Anna Kaksonen, Jing Sun, Adam Siade, Anna Yusov, Benjamin C Bostick
Microbially driven nitrate-dependent iron (Fe) oxidation (NDFO) in subsurface environments has been intensively studied. However, the extent to which Fe(II) oxidation is biologically catalyzed remains unclear because no neutrophilic iron-oxidizing and nitrate reducing autotroph has been isolated to confirm the existence of an enzymatic pathway. While mixotrophic NDFO bacteria have been isolated, understanding the process is complicated by simultaneous abiotic oxidation due to nitrite produced during denitrification...
April 20, 2018: Environmental Science & Technology
Anne Leinweber, Michael Weigert, Rolf Kümmerli
Phenotypic plasticity in response to competition is a well-described phenomenon in higher organisms. Here, we show that also bacteria have the ability to sense the presence of competitors and mount fine-tuned responses to match prevailing levels of competition. In our experiments, we studied inter-specific competition for iron between the bacterium Pseudomonas aeruginosa (PA) and its competitor Burkholderia cenocepacia (BC). We focused on the ability of PA to phenotypically adjust the production of pyoverdine, an iron-scavenging siderophore...
April 17, 2018: Evolution; International Journal of Organic Evolution
Noah Stern, Jacqueline Mejia, Shaomei He, Yu Yang, Matthew Ginder-Vogel, Eric E Roden
Dissimilatory iron-reducing bacteria (DIRB) are known to use humic substances (HS) as electron shuttles for dissimilatory iron reduction (DIR) by transferring electrons to HS-quinone moieties, which in turn rapidly reduce Fe(III) oxides. It has also been proposed that certain components of HS can be mineralized by microorganisms. However, the potential for HS to serve a source of organic carbon (OC) that fuels DIR is unknown. We studied whether isolated humic acids (HA) and humins (HM) could serve as both electron shuttles and electron donors for DIR by freshwater sediment microorganisms...
April 16, 2018: Environmental Science & Technology
Galimzhan Kalihanovich Duskaev, Nadezhda Mihajlovna Kazachkova, Alexander Sergeevich Ushakov, Baer Serekpaevich Nurzhanov, Albert Farhitdinovich Rysaev
Aim: Modern methods of producing poultry meat without the use of antibiotics are known, and it is possible to achieve the desired conditions, including the use of herbal preparations. In addition, it is known that metabolites of medicinal plants are inhibitors of the quorum sensing system in bacteria. The aim of the present study was to determine the effect of Quercus cortex extract in a reduced dose on the productivity and body state of healthy chicken broilers. Materials and Methods: For the experiment, 120 heads of 7-day-old healthy broiler chickens were selected, and they were divided into four groups (n=30, 3 replicates of 10 birds in each group) by the analog method...
February 2018: Veterinary World
Zhenyu Jin, Jiahong Li, Lei Ni, Rongrong Zhang, Aiguo Xia, Fan Jin
Understanding the mechanisms that promote cooperative behaviors of bacteria in their hosts is of great significance to clinical therapies. Environmental stress is generally believed to increase competition and reduce cooperation in bacteria. Here, we show that bacterial cooperation can in fact be maintained because of environmental stress. We show that Pseudomonas aeruginosa regulates the secretion of iron-scavenging siderophores in the presence of different environmental stresses, reserving this public good for private use in protection against reactive oxygen species when under stress...
April 11, 2018: Nature Communications
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