共查询到20条相似文献,搜索用时 156 毫秒
1.
Pedro Leão Lucas Le Nagard Hao Yuan Jefferson Cypriano Inácio Da Silva-Neto Dennis A. Bazylinski Daniel Acosta-Avalos Henrique L. de Barros Adam P. Hitchcock Ulysses Lins Fernanda Abreu 《Environmental microbiology》2020,22(4):1495-1506
The most well-recognized magnetoreception behaviour is that of the magnetotactic bacteria (MTB), which synthesize membrane-bounded magnetic nanocrystals called magnetosomes via a biologically controlled process. The magnetic minerals identified in prokaryotic magnetosomes are magnetite (Fe3O4) and greigite (Fe3S4). Magnetosome crystals, regardless of composition, have consistent, species-specific morphologies and single-domain size range. Because of these features, magnetosome magnetite crystals possess specific properties in comparison to abiotic, chemically synthesized magnetite. Despite numerous discoveries regarding MTB phylogeny over the last decades, this diversity is still considered underestimated. Characterization of magnetotactic microorganisms is important as it might provide insights into the origin and establishment of magnetoreception in general, including eukaryotes. Here, we describe the magnetotactic behaviour and characterize the magnetosomes from a flagellated protist using culture-independent methods. Results strongly suggest that, unlike previously described magnetotactic protists, this flagellate is capable of biomineralizing its own anisotropic magnetite magnetosomes, which are aligned in complex aggregations of multiple chains within the cell. This organism has a similar response to magnetic field inversions as MTB. Therefore, this eukaryotic species might represent an early origin of magnetoreception based on magnetite biomineralization. It should add to the definition of parameters and criteria to classify biogenic magnetite in the fossil record. 相似文献
2.
Background
Magnetotactic bacteria have long intrigued researchers because they synthesize intracellular nano-scale (40-100 nm) magnetic particles composed of Fe3O4, termed magnetosomes. Current research focuses on the molecular mechanisms of bacterial magnetosome formation and its practical applications in biotechnology and medicine. Practical applications of magnetosomes are based on their ferrimagnetism, nanoscale size, narrow size distribution, dispersal ability, and membrane-bound structure. However, the applications of magnetosomes have not yet been developed commercially, mainly because magnetotactic bacteria are difficult to cultivate and consistent, high yields of magnetosomes have not yet been achieved. 相似文献3.
Fernanda Abreu Mauricio E Cant?o Marisa F Nicolás Fernando G Barcellos Viviana Morillo Luiz GP Almeida Fabrícia F do Nascimento Christopher T Lefèvre Dennis A Bazylinski Ana Tereza R de Vasconcelos Ulysses Lins 《The ISME journal》2011,5(10):1634-1640
Magnetosomes are prokaryotic organelles produced by magnetotactic bacteria that consist of nanometer-sized magnetite (Fe3O4) or/and greigite (Fe3S4) magnetic crystals enveloped by a lipid bilayer membrane. In magnetite-producing magnetotactic bacteria, proteins present in the magnetosome membrane modulate biomineralization of the magnetite crystal. In these microorganisms, genes that encode for magnetosome membrane proteins as well as genes involved in the construction of the magnetite magnetosome chain, the mam and mms genes, are organized within a genomic island. However, partially because there are presently no greigite-producing magnetotactic bacteria in pure culture, little is known regarding the greigite biomineralization process in these organisms including whether similar genes are involved in the process. Here using culture-independent techniques, we now show that mam genes involved in the production of magnetite magnetosomes are also present in greigite-producing magnetotactic bacteria. This finding suggest that the biomineralization of magnetite and greigite did not have evolve independently (that is, magnetotaxis is polyphyletic) as once suggested. Instead, results presented here are consistent with a model in which the ability to biomineralize magnetosomes and the possession of the mam genes was acquired by bacteria from a common ancestor, that is, the magnetotactic trait is monophyletic. 相似文献
4.
Edouard Alphandéry Matthieu Amor Fran?ois Guyot Imène Chebbi 《Applied microbiology and biotechnology》2012,96(3):663-670
The introduction of various iron-chelating agents to the Magnetospirillum magneticum strain AMB-1 bacterial growth medium stimulated the growth of M. magneticum strain AMB-1 magnetotactic bacteria and enhanced the production of magnetosomes. After 7?days of growth, the number of bacteria and the production of magnetosomes were increased in the presence of iron-chelating agents by factors of up to ??2 and ??6, respectively. The presence of iron-chelating agents also produced an increase in magnetosome size and chain length and yielded improved magnetosome heating properties. The specific absorption rate of suspensions of magnetosome chains isolated from M. magneticum strain AMB-1 magnetotactic bacteria, measured under the application of an alternating magnetic field of average field strength ??20?mT and frequency 198?kHz, increased from ??222?W/gFe in the absence of iron-chelating agent up to ??444?W/gFe in the presence of 4???M rhodamine B and to ??723?W/gFe in the presence of 4???M EDTA. These observations were made at an iron concentration of 20???M and iron-chelating agent concentrations below 40???M. 相似文献
5.
6.
Dennis A. Bazylinski Anthony J. Garratt-Reed Afshin Abedi Richard B. Frankel 《Archives of microbiology》1993,160(1):35-42
Greigite (Fe3S4) and pyrite (FeS2) particles in the magnetosomes of a many-celled, magnetotactic prokaryote (MMP), common in brackish-to-marine, sulfidic, aquatic habitats, contained relatively high concentrations of copper which ranged from about 0.1 to 10 atomic per cent relative to iron. In contrast, the greigite particles in the magnetosomes of a curved magnetotactic bacterium collected from the same sampling site did not contain significant levels of copper. The ability of the MMP to biomineralize copper within its magnetosomes appeared to be limited to that organism and dependent upon the site from which it was collected. Although the chemical mechanism and physiological function of copper accumulation in the magnetosomes of the MMP is unclear, the presence of copper is the first evidence that another transition metal ion could be incorporated in the mineral phase of the magnetosomes of a magnetotactic bacterium.Abbreviation MMP
many-celled magnetotactic prokaryote 相似文献
7.
Pseudomonas mendocina MCM B-402 was found to utilize a triphenylmethane dye, methyl violet as the sole source of carbon when incorporated in synthetic
medium. Almost complete decolorization of methyl violet by P. mendocina was observed within 48 h of incubation at ambient temperature (28 ± 2 °C) under aerated culture conditions, when the bacteria
were inoculated into Davis Mingioli's synthetic medium at a concentration of 100 mg/l medium. Methyl violet was mineralized
to CO2 through three unknown intermediate metabolites and phenol. The decolorization of the dye involved demethylation.
Received: 27 November 1998 / Received revision: 2 March 1999 / Accepted: 5 March 1999 相似文献
8.
Magnetosomes are intracellular structures produced by magnetotactic bacteria and are magnetic nanoparticles surrounded by a lipid bilayer membrane. Magnetosomes reportedly possess intrinsic enzyme mimetic activity similar to that found in horseradish peroxidase (HRP) and can scavenge reactive oxygen species depending on peroxidase activity. Our previous study has demonstrated the phototaxis characteristics of Magnetospirillum magneticum strain AMB-1 cells, but the mechanism is not well understood. Therefore, we studied the relationship between visible-light irradiation and peroxidase-like activity of magnetosomes extracted from M. magneticum strain AMB-1. We then compared this characteristic with that of HRP, iron ions, and naked magnetosomes using 3,3′,5,5′-tetramethylbenzidine as a peroxidase substrate in the presence of H2O2. Results showed that HRP and iron ions had different activities from those of magnetosomes and naked magnetosomes when exposed to visible-light irradiation. Magnetosomes and naked magnetosomes had enhanced peroxidase-like activities under visible-light irradiation, but magnetosomes showed less affinity toward substrates than naked magnetosomes under visible-light irradiation. These results suggested that the peroxidase-like activity of magnetosomes may follow an ordered ternary mechanism rather than a ping–pong mechanism. This finding may provide new insight into the function of magnetosomes in the phototaxis in magnetotactic bacteria. 相似文献
9.
Animal waste causes environmental problems like eutrophication of ground and surface water or the pollution of the atmosphere
because of its high NH4
+ content. The aim of our study was to fix the nitrogen of swine waste as biomass. Therefore, an isolated alga, Chlorella sp., and bacteria naturally living in liquid manure were grown in batch cultures (containing diluted swine waste supplied
with a nutrient solution) and continuous cultures (undiluted liquid manure) to achieve reduction of NH4
+ and total organic carbon (TOC) contents. For continuous cultivation, a photobioreactor of our own design was used. The batch
cultivation of Chlorella sp. and bacteria in swine waste resulted in good growth of both groups of organisms and in a reduction of 25% NH4
+ and 80% TOC. In the continuous cultivation a steady state was not achieved owing to a change in the composition of the bacterial
population. NH4
+ was totally removed, but NO2
− (up to 100 mM) was transiently released. NO3
− was not detected. These effects might be explained by the presence of heterotrophic nitrifiers, which are able to oxidize
NH4
+ to NO2
− and to reduce NO2
− to gaseous compounds.
Received: 21 January 1999 / Received revision: 9 March 1999 / Accepted: 14 March 1999 相似文献
10.
Hirokazu Shimoshige Hideki Kobayashi Toru Mizuki Yutaka Nagaoka Akira Inoue Toru Maekawa 《PloS one》2015,10(5)
Magnetotactic bacteria (MTB) synthesize intracellular magnetic nanocrystals called magnetosomes, which are composed of either magnetite (Fe3O4) or greigite (Fe3S4) and covered with lipid membranes. The production of magnetosomes is achieved by the biomineralization process with strict control over the formation of magnetosome membrane vesicles, uptake and transport of iron ions, and synthesis of mature crystals. These magnetosomes have high potential for both biotechnological and nanotechnological applications, but it is still extremely difficult to grow MTB and produce a large amount of magnetosomes under the conventional cultural conditions. Here, we investigate as a first attempt the effect of polyethylene glycol (PEG) added to the culture medium on the increase in the yield of magnetosomes formed in Magnetospirillum magnetotacticum MS-1. We find that the yield of the formation of magnetosomes can be increased up to approximately 130 % by adding PEG200 to the culture medium. We also measure the magnetization of the magnetosomes and find that the magnetosomes possess soft ferromagnetic characteristics and the saturation mass magnetization is increased by 7 %. 相似文献
11.
Christopher T. Lefèvre Denis Trubitsyn Fernanda Abreu Sebastian Kolinko Christian Jogler Luiz Gonzaga Paula de Almeida Ana Tereza R. de Vasconcelos Michael Kube Richard Reinhardt Ulysses Lins David Pignol Dirk Schüler Dennis A. Bazylinski Nicolas Ginet 《Environmental microbiology》2013,15(10):2712-2735
Magnetotactic bacteria (MTB) represent a group of diverse motile prokaryotes that biomineralize magnetosomes, the organelles responsible for magnetotaxis. Magnetosomes consist of intracellular, membrane‐bounded, tens‐of‐nanometre‐sized crystals of the magnetic minerals magnetite (Fe3O4) or greigite (Fe3S4) and are usually organized as a chain within the cell acting like a compass needle. Most information regarding the biomineralization processes involved in magnetosome formation comes from studies involving Alphaproteobacteria species which biomineralize cuboctahedral and elongated prismatic crystals of magnetite. Many magnetosome genes, the mam genes, identified in these organisms are conserved in all known MTB. Here we present a comparative genomic analysis of magnetotactic Deltaproteobacteria that synthesize bullet‐shaped crystals of magnetite and/or greigite. We show that in addition to mam genes, there is a conserved set of genes, designated mad genes, specific to the magnetotactic Deltaproteobacteria, some also being present in Candidatus Magnetobacterium bavaricum of the Nitrospirae phylum, but absent in the magnetotactic Alphaproteobacteria. Our results suggest that the number of genes associated with magnetotaxis in magnetotactic Deltaproteobacteria is larger than previously thought. We also demonstrate that the minimum set of mam genes necessary for magnetosome formation in Magnetospirillum is also conserved in magnetite‐producing, magnetotactic Deltaproteobacteria. Some putative novel functions of mad genes are discussed. 相似文献
12.
The biomineralization of magnetosomes in <Emphasis Type="Italic">Magnetospirillum gryphiswaldense</Emphasis> 总被引:8,自引:0,他引:8
D. Schüler 《International microbiology》2002,5(4):209-214
Magnetotactic bacteria (MTB) are major constituents of natural microbial communities in sediments and chemically stratified
water columns. The ability of MTB to migrate along magnetic field lines is based on specific intracellular structures, the
magnetosomes, which, in most MTB, are nanometer-sized, membrane-bound magnetic particles consisting of the iron mineral magnetite
(Fe3O4). A broad diversity of morphological forms has been found in various MTB. The unique characteristics of bacterial magnetosomes
have attracted a broad interdisciplinary research interest. The magnetosome membrane (MM) in Magnetospirillum gryphiswaldense contains a number of specific Mam proteins. Several mam genes were analyzed and assigned to different genomic regions. Many of the Mam proteins are highly conserved in other MTB
but display low sequence similarity to any proteins from nonmagnetic organisms.
Electronic Publication 相似文献
13.
Xiaohui Zhu Lucas Le Nagard Dennis A. Bazylinski Viviana Morillo Fernanda Abreu 《Geomicrobiology journal》2018,35(3):215-226
Scanning transmission X-ray microscopy at the Fe 2p (L2,3), O1s, C1s, and S2p edges was used to study greigite magnetosomes and other cellular content of a magnetotactic bacterium known as a multicellular magnetotactic prokaryote (MMP). X-ray absorption spectrum (XAS) and X-ray magnetic circular dichroism (XMCD) spectra of greigite (Fe3S4) nanoparticles, synthesized via a hydrothermal method, were measured. Although XAS of the synthetic greigite nanoparticles and biotic magnetosome crystals in MMPs are slightly different due to partial oxidation of the MMP greigite, the XMCD spectra of the two materials are in good agreement. The Fe 2p XAS and XMCD spectra of Fe3S4 are quite different from those of its oxygen analog, magnetite (Fe3O4), suggesting Fe3S4 has a different electronic and magnetic structure than Fe3O4 despite having the same crystal structure. Sulfate and sulfide species were also identified in MMPs, both of which are likely involved in sulfur metabolism. 相似文献
14.
Yasmina Hamdous Imène Chebbi Chalani Mandawala Raphael Le Fèvre François Guyot Olivier Seksek Edouard Alphandéry 《Journal of nanobiotechnology》2017,15(1):74
Background
Biologics magnetics nanoparticles, magnetosomes, attract attention because of their magnetic characteristics and potential applications. The aim of the present study was to develop and characterize novel magnetosomes, which were extracted from magnetotactic bacteria, purified to produce apyrogen magnetosome minerals, and then coated with Chitosan, Neridronate, or Polyethyleneimine. It yielded stable magnetosomes designated as M-Chi, M-Neri, and M-PEI, respectively. Nanoparticle biocompatibility was evaluated on mouse fibroblast cells (3T3), mouse glioblastoma cells (GL-261) and rat glioblastoma cells (RG-2). We also tested these nanoparticles for magnetic hyperthermia treatment of tumor in vitro on two tumor cell lines GL-261 and RG-2 under the application of an alternating magnetic field. Heating, efficacy and internalization properties were then evaluated.Results
Nanoparticles coated with chitosan, polyethyleneimine and neridronate are apyrogen, biocompatible and stable in aqueous suspension. The presence of a thin coating in M-Chi and M-PEI favors an arrangement in chains of the magnetosomes, similar to that observed in magnetosomes directly extracted from magnetotactic bacteria, while the thick matrix embedding M-Neri leads to structures with an average thickness of 3.5 µm2 per magnetosome mineral. In the presence of GL-261 cells and upon the application of an alternating magnetic field, M-PEI and M-Chi lead to the highest specific absorption rates of 120–125 W/gFe. Furthermore, while M-Chi lead to rather low rates of cellular internalization, M-PEI strongly associate to cells, a property modulated by the application of an alternating magnetic field.Conclusions
Coating of purified magnetosome minerals can therefore be chosen to control the interactions of nanoparticles with cells, organization of the minerals, as well as heating and cytotoxicity properties, which are important parameters to be considered in the design of a magnetic hyperthermia treatment of tumor.15.
A. W. E. Dilg Giovanna Mincione Klaus Achterhold Olga Iakovleva Matthias Mentler Claudio Luchinat Ivano Bertini F. G. Parak 《Journal of biological inorganic chemistry》1999,4(6):727-741
4 S4]3 + and the reduced [Fe4S4]2 + clusters in the high-potential iron protein I from Ectothiorhodospira halophila were measured in a temperature range from 5 K to 240 K. EPR measurements and 57Fe electron-nuclear double resonance (ENDOR) experiments were carried out with the oxidized protein. In the oxidized state
the cluster has a net spin S = 1/2 and is paramagnetic. As common in [Fe4S4]3 + clusters, the M?ssbauer spectrum was simulated with two species contributing equally to the absorption area: two Fe3 + atoms couple to the “ferric-ferric” pair, and one Fe2 + and one Fe3 + atom give the “ferric-ferrous pair”. For the simulation of the M?ssbauer spectrum, g-values were taken from EPR measurements. A-tensor components were determined by 57Fe ENDOR experiments that turned out to be a necessary source of estimating parameters independently. In order to obtain a
detailed agreement of M?ssbauer and ENDOR data, electronic relaxation has to be taken into account. Relaxing the symmetry
condition in a way that the electric field gradient tensor does not coincide with g- and A-tensors yielded an even better agreement of experimental and theoretical M?ssbauer spectra. Spin-spin and spin-lattice relaxation
times were estimated by pulsed EPR; the former turned out to be the dominating mechanism at T = 5 K. Relaxation times measured by pulsed EPR and obtained from the M?ssbauer fit were compared and yield nearly identical
values. The reduced cluster has one additional electron and has a diamagnetic (S = 0) ground state. All the four irons are indistinguishable in the M?ssbauer spectrum, indicating a mixed-valence state of
Fe2.5 + for each.
Received: 15 February 1999 / Accepted: 31 August 1999 相似文献
16.
A. De Smul J. Dries L. Goethals H. Grootaerd W. Verstraete 《Applied microbiology and biotechnology》1997,48(3):297-303
In a mesophilic (30–35 °C), sulphidogenic, ethanol-fed expanded-granular-sludge-blanket reactor, sulphate, at loading rates
of up to 10.0–12.0 g Sl−1␣day−1, was removed with an average efficiency of more than 80%. The pH was between 7.7 and 8.3 and the maximal total dissolved
sulphide concentration was up to 20 mM S (650 mg S/l). The alkaline pH was maintained by either a pH-control unit with sodium
hydroxide or by stripping part of the sulphide and CO2 from the recycle with nitrogen gas. The superficial upstream liquid velocity (v
up) was 3.0–4.5 m/h. The ratio of ethanol to sulphur was near stoichiometry. At alkaline pH, the activity of the acetotrophic
sulphate-reducing bacteria, growing on acetate, was strongly enhanced, whereas at pH below 7.7 the acetotrophic sulphate-reducing
bacteria were inhibited by aqueous H2S. With regard to the removal efficiency and operational stability, external stripping with N2 and pH control were equally successful.
Received: 2 December 1996 / Received revision: 13 March 1997 / Accepted: 15 March 1997 相似文献
17.
The ferrous iron oxidation kinetics of Thiobacillus ferrooxidans in batch cultures was examined, using on-line off-gas analyses to measure the oxygen and carbon dioxide consumption rates
continuously. A cell suspension from continuous cultures at steady state was used as the inoculum. It was observed that a
dynamic phase occurred in the initial phase of the experiment. In this phase the bacterial ferrous iron oxidation and growth
were uncoupled. After about 16 h the bacteria were adapted and achieved a pseudo-steady state, in which the specific growth
rate and oxygen consumption rate were coupled and their relationship was described by the Pirt equation. In pseudo-steady
state, the growth and oxidation kinetics were accurately described by the rate equation for competitive product inhibition.
Bacterial substrate consumption is regarded as the primary process, which is described by the equation for competitive product
inhibition. Subsequently the kinetic equation for the specific growth rate, μ, is derived by applying the Pirt equation for bacterial substrate consumption and growth. The maximum specific growth rate,
μ
max, measured in the batch culture agrees with the dilution rate at which washout occurs in continuous cultures. The maximum
oxygen consumption rate, q
O2,max, of the cell suspension in the batch culture was determined by respiration measurements in a biological oxygen monitor at
excess ferrous iron, and showed changes of up to 20% during the course of the experiment. The kinetic constants determined
in the batch culture slightly differ from those in continuous cultures, such that, at equal ferric to ferrous iron concentration
ratios, biomass-specific rates are up to 1.3 times higher in continuous cultures.
Received: 8 February 1999 / Accepted: 17 February 1999 相似文献
18.
Elena Babini Marco Borsari Francesco Capozzi Lindsay D. Eltis C. Luchinat 《Journal of biological inorganic chemistry》1999,4(6):692-700
The amide group between residues 78 and 79 of Chromatium vinosum high-potential iron-sulfur protein (HiPIP) is in close proximity to the Fe4S4 cluster of this protein and interacts via a hydrogen bond with Sγ of Cys77, one of the cluster ligands. The reduction potential
of the S79P variant was 104±3 mV lower than that of the recombinant wild-type (rcWT) HiPIP (5 mM phosphate, 100 mM NaCl, pH 7,
293 K), principally due to a decrease in the enthalpic term which favors the reduction of the rcWT protein. Analysis of the
variant protein by NMR spectroscopy indicated that the substitution has little effect on the structure of the HiPIP or on
the electron distribution in the oxidized cluster. Potential energy calculations indicate that the difference in reduction
potential between rcWT and S79P variant HiPIPs is due to the different electrostatic properties of amide 79 in these two proteins.
These results suggest that the influence of amide group 79 on the reduction potential of C. vinosum HiPIP is a manifestation of a general electrostatic effect rather than a specific interaction. More generally, these results
provide experimental evidence for the importance of buried polar groups in determining the reduction potentials of metalloproteins.
Received: 26 April 1999 / Accepted: 24 August 1999 相似文献
19.
Amino acids have been produced with the aid of microorganisms for nearly 40 years now. The economic importance of these cellular
building blocks is enormous. Demand for them is rising continuously and currently more than 106 tonnes/year are required. Continual efforts to increase production performance are directed towards the microorganisms themselves,
as well as towards technical improvements of the respective processes. A special position within the amino-acid-producing
microorganisms is traditionally occupied by Corynebacterium glutamicum. Molecular research in conjunction with NMR studies of flux has revealed fascinating new properties of this particular organism,
including the existence of a new type of exporter and reverse fluxes within the anaplerosis. The knowledge gained will enable
the further improvement of production strains and furthermore extend fundamental insights into metabolite flux management
within bacteria in general.
Received: 8 December 1998 / Received revision: 1 March 1999 / Accepted: 5 March 1999 相似文献
20.
Formation of magnetosomes in magnetotactic bacteria 总被引:1,自引:0,他引:1
Schüler D 《Journal of molecular microbiology and biotechnology》1999,1(1):79-86
The ability of magnetotactic bacteria to orient and migrate along geomagnetic field lines is based on intracellular magnetic structures, the magnetosomes, which comprise nano-sized, membrane bound crystals of magnetic iron minerals. The formation of magnetosomes is achieved by a biological mechanism that controls the accumulation of iron and the biomineralization of magnetic crystals with a characteristic size and morphology within membrane vesicles. This paper focuses on the current knowledge about magnetotactic bacteria and will outline aspects of the physiology and molecular biology of magnetosome formation. The biotechnological potential of the biomineralization process is discussed. 相似文献