نتایج جستجو برای: magnetotactic bacteria
تعداد نتایج: 180391 فیلتر نتایج به سال:
Magnetotactic bacteria (MTB) in the phylum Nitrospirae synthesize up to hundreds of intracellular bullet-shaped magnetite magnetosomes. In the present study, a watermelon-shaped magnetotactic bacterium (designated MWB-1) from Lake Beihai in Beijing, China, was characterized. This uncultivated microbe was identified as a member of the phylum Nitrospirae and represents a novel phylogenetic lineag...
A magnetic force microscope �MFM� was used to image topography and magnetic forces from a chain of submicron single magnetic domain particles produced by and contained in isolated magnetotactic bacteria. The noncontact magnetic force microscope data were used to determine a value for the magnetic moment of an individual bacterial cell, of order 10 emu, consistent with the average magnetic momen...
A targeted metagenomic approach was applied to investigate magnetotactic bacteria (MTB) within the phylum Nitrospirae in Lake Miyun near Beijing, China. Five fosmids containing rRNA operons were identified. Comparative sequence analysis of a total of 172 kb provided new insights into their genome organization and revealed unexpected subgenomic diversity of uncultivated MTB in the phylum Nitrosp...
The biomineralization of several magnetic iron minerals, including the iron oxide magnetite (Fe30 4 ; Fe 2I Fe/+04 ) and the iron sulfides greigite (Fe3S4 ) and pyrrhotite (Fe7SS)' can be mediated by bacteria as well as by other organisms. These minerals are known to be synthesized by procaryotes in one of two fundamentally different modes of biomineralization. The first is uncontrolled mineral...
Aquatic, motile bacteria that orient and rate along geomagnetic field Iines,known as gnetotactic bacteria, were discovered three de cades ago by Richard P. Blakemore, then a uate student at the University of Massachusetts at Amherst, Initially considered a mere osity, these bacteria have gained celebrity tus as well as deeper respect among scientists, engineers, and the general public. Thus, ma...
The room temperature co-precipitation of ferrous and ferric iron under alkaline conditions typically yields superparamagnetic magnetite nanoparticles below a size of 20 nm. We show that at pH = 9 this method can be tuned to grow larger particles with single stable domain magnetic (> 20-30 nm) or even multi-domain behavior (> 80 nm). The crystal growth kinetics resembles surprisingly observati...
Off-axis electron holography in the transmission electron microscope was used to correlate the physical and magnetic microstructure of magnetite nanocrystals in magnetotactic bacteria. The magnetite crystals were all single magnetic domains, and the magnetization directions of small superparamagnetic crystals were constrained by magnetic interactions with larger crystals in the chains. Shape an...
Distinct magnetic properties of marine sediments that record the Palaeocene–Eocene thermal maximum (PETM) have been suggested to be due to a bacterial magnetofossil signal that is linked to enhanced weathering conditions during the PETM. We document the dominance of bacterial magnetite in deep-sea sediments from southern Kerguelen Plateau (Ocean Drilling Program Hole 738C, southern magnetofossi...
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