Magnetosomes

Stolz, John F.

doi:10.1099/00221287-139-8-1663

Cited by 35 publications

(13 citation statements)

References 25 publications

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“…In cocci collected in the same region (Spring et al, 1998), magnetosomes are arranged in one single chain with larger particles in the middle and smaller particles in the end. However, distribution of width over length varied linearly as in most magnetotactic bacteria reported (Bazylinski, 1995;Farina et al, 1994;Mann et al, 1990c;Stolz, 1993). Mann et al (1987) reported differences in aspect ratios of mature and immature bullet-shaped magnetosomes.…”

Section: Discussionmentioning

confidence: 89%

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Magnetosome size distribution in uncultured rod-shaped bacteria as determined by electron microscopy and electron spectroscopic imaging

Lins¹,

Farina²

1998

Microsc. Res. Tech.

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Section: Discussionmentioning

confidence: 89%

“…A biological membrane surrounds each magnetic particle, and forms a magnetosome (Stolz, 1993). The magnetic particles of magnetosomes consist of either iron oxide magnetite (Fe 3 O 4 ) or iron sulfide mineral phases Mann et al, 1990a).…”

Section: Introductionmentioning

confidence: 99%

Magnetosome size distribution in uncultured rod-shaped bacteria as determined by electron microscopy and electron spectroscopic imaging

Lins¹,

Farina²

1998

Microsc. Res. Tech.

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“…The observed magnetosomes were up to 200 nm in length and 160 nm in width and, therefore, almost twice as big as magnetosomes found in most other magnetic bacteria, which normally have sizes ranging from 40 to 120 nm (Chang et al 1989;Mann et al 1990). The newly discovered magnetosomes were considered unusual because it was originally thought that the narrow size range of magnetosomes corresponds to the theoretically determined size limits of single-domain magnetite (Kirschvink 1983;Stolz 1993) as calculated by Butler and Banerjee (1975). According to these calculations, the newly discovered magnetosomes were classified as potentially consisting of two magnetic domains, which would result in a drastic reduction of their permanent magnetic dipole moment.…”

Section: Introductionmentioning

confidence: 97%

Phylogenetic affiliation and ultrastructure of uncultured magnetic bacteria with unusually large magnetosomes

Spring

Lins

Amann

et al. 1998

Archives of Microbiology

114

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Natural enrichments of magnetic bacteria from the Itaipu lagoon near Rio de Janeiro were dominated by coccoid-to-ovoid morphotypes that produced unusually large magnetosomes. To determine the phylogenetic position of these unusual microorganisms, 16S rRNA genes were retrieved from bacteria magnetically separated from sediment of the Itaipu lagoon by in vitro amplification and cloning of PCR products into a plasmid vector. Partial sequencing of the obtained clones revealed two clusters of closely related sequences affiliated to a distinct lineage consisting exclusively of magnetic bacteria within the alpha-subclass of Proteobacteria. For a detailed phylogenetic analysis, several almost complete sequences of the 16S rRNA genes were determined. One representative clone of each cluster provided a PCR template for the in vitro transcription of group-specific polynucleotide probes complementary to a variable region of the 16S rRNA molecule. At least three different morphotypes of magnetic bacteria were reliably identified by post-embedding hybridization of ultra-thin sections. Electron microscopic analyses of hybridized cells enabled for the first time a detailed description of the morphological variety and ultrastructure of phylogenetically identified, uncultured magnetic bacteria. Two distinct coccoid bacteria were identified by the transcript probe complementary to the 16S rRNA sequence mabrj12, whereas the probe complementary to the sequence mabrj58 allowed the identification of an ovoid morphotype that displayed magnetosomes with the largest volumes observed to date.

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“…tel~ned magiletofossils (4), as determined by electron microscopy of magnetic material separated from sediineilts and soils, has been used to identifq. the presence of magnetotactic bacteria (5). These appareiltly unique clystal forms of Fe30, have been used to distinguish a bacterial (intracel-polycarbonate bottles filled with the LB growth media, 0.5 g of ferrihydrite, and 5 X l o 6 cells/ml.…”

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confidence: 99%

Oxygen and Iron Isotope Studies of Magnetite Produced by Magnetotactic Bacteria

Mandernack

Bazylinski

Shanks

et al. 1999

Science

133

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A series of carefully controlled laboratory studies was carried out to investigate oxygen and iron isotope fractionation during the intracellular production of magnetite (Fe(3)O(4)) by two different species of magnetotactic bacteria at temperatures between 4 degrees and 35 degrees C under microaerobic and anaerobic conditions. No detectable fractionation of iron isotopes in the bacterial magnetites was observed. However, oxygen isotope measurements indicated a temperature-dependent fractionation for Fe(3)O(4) and water that is consistent with that observed for Fe(3)O(4) produced extracellularly by thermophilic Fe(3+)-reducing bacteria. These results contrast with established fractionation curves estimated from either high-temperature experiments or theoretical calculations. With the fractionation curve established in this report, oxygen-18 isotope values of bacterial Fe(3)O(4) may be useful in paleoenvironmental studies for determining the oxygen-18 isotope values of formation waters and for inferring paleotemperatures.

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Magnetosomes

Cited by 35 publications

References 25 publications

Magnetosome size distribution in uncultured rod-shaped bacteria as determined by electron microscopy and electron spectroscopic imaging

Magnetosome size distribution in uncultured rod-shaped bacteria as determined by electron microscopy and electron spectroscopic imaging

Phylogenetic affiliation and ultrastructure of uncultured magnetic bacteria with unusually large magnetosomes

Oxygen and Iron Isotope Studies of Magnetite Produced by Magnetotactic Bacteria

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