Dependence of bacterial magnetosome morphology on chemical conditions in deep-sea sediments

Yamazaki, T.; Suzuki, Yohey; Kouduka, Mariko; Kawamura, Noboru

doi:10.1016/j.epsl.2019.02.015

Cited by 31 publications

(41 citation statements)

References 52 publications

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“…It should be noted that the physical (e.g., morphology and crystal size distribution), chemical (e.g., stoichiometry and cation‐substitution), and even crystallographic features of magnetosomal magnetite could be modified to some extent by the environments in which MTB live (Faivre et al, 2008; Lefèvre et al, 2016; Li et al, 2016; Li & Pan, 2012; Olszewska‐Widdrat et al, 2019). Microscopic identifications of magnetofossils tend to rely on morphological recognition based on conventional TEM observations (Chang et al, 2018; Li, Benzerara, et al, 2013; Yamazaki et al, 2019), which fail to acquire detailed information on crystal growth and habit and sometimes result in magnetofossil misidentification (Buseck et al, 2001). Therefore, additional systematic studies of magnetosomal crystals in both modern MTB and magnetotactic eukaryotes, and magnetofossils from ancient sediments with various combined advanced TEM and STXM approaches are vital (Buseck et al, 2001; Kalirai et al, 2013; Leão et al, 2020; Li, Benzerara, et al, 2013; Zhu et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

“…Fossil remains of MTB called magnetofossils have been found widely in Cenozoic sediments (Roberts et al, 2012) and have even been identified in pre‐Cambrian rocks (Kopp & Kirschvink, 2008). Magnetosomal magnetite has distinctive physical, chemical, crystallographic, and magnetic properties that contrast with those of detrital and other types of magnetite (Amor et al, 2015; Kopp & Kirschvink, 2008; Li, Benzerara, et al, 2013; Moskowitz et al, 1993), which make magnetofossils important and ideal carriers of paleomagnetic and paleoenvironmental signals (Chang et al, 2018; Larrasoaña et al, 2014; Roberts et al, 2011; Usui et al, 2017; Yamazaki et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…We focus here on bullet‐shaped magnetite mainly because it is thought to be (1) the first and oldest crystal type biomineralized by ancient MTB (Lefèvre, Trubitsyn, Abreu, Kolinko, de Almeida, & de Vasconcelos, 2013; Lin et al, 2017), (2) the geologically best preserved magnetofossil type (Lefèvre, Pósfai, et al, 2011; Li et al, 2015, 2010; Mann et al, 1987), and (3) a sensitive proxy for reduced environmental oxygen (Mao et al, 2014; Yamazaki et al, 2019). Moreover, compared to magnetotactic Nitrospirae (Li et al, 2010, 2015), crystal growth and chain assembly of bullet‐shaped magnetite within the magnetotactic Deltaproteobacteria have not been studied systematically.…”

Section: Introductionmentioning

confidence: 99%

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Bullet‐Shaped Magnetite Biomineralization Within a Magnetotactic Deltaproteobacterium: Implications for Magnetofossil Identification

Menguy

Roberts

et al. 2020

JGR Biogeosciences

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Magnetite produced by magnetotactic bacteria (MTB) provides stable paleomagnetic signals because it occurs as natural single‐domain magnetic nanocrystals. MTB can also provide useful paleoenvironmental information because their crystal morphologies are associated with particular bacterial groups and the environments in which they live. However, identification of the fossil remains of MTB (i.e., magnetofossils) from ancient sediments or rocks is challenging because of their generally small sizes and because the growth, morphology, and chain assembly of magnetite within MTB are not well understood. Nanoscale characterization is, therefore, needed to understand magnetite biomineralization and to develop magnetofossils as biogeochemical proxies for paleoenvironmental reconstructions. Using advanced transmission electron microscopy, we investigated magnetite growth and chain arrangements within magnetotactic Deltaproteobacteria strain WYHR‐1, which reveals how the magnetite grows to form elongated, bullet‐shaped nanocrystals. Three crystal growth stages are recognized: (i) initial isotropic growth to produce nearly round ~20 nm particles, (ii) subsequent anisotropic growth along the [001] crystallographic direction to ~75 nm lengths and ~30–40 nm widths, and (iii) unidirectional growth along the [001] direction to ~180 nm lengths, with some growing to ~280 nm. Crystal growth and habit differ from that of magnetite produced by other known MTB strains, which indicates species‐specific biomineralization. These findings suggest that magnetite biomineralization might be much more diverse among MTB than previously thought. When characterized adequately at species level, magnetofossil crystallography, and apomorphic features are, therefore, likely to become useful proxies for ancient MTB taxonomic groups or species and for interpreting the environments in which they lived.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bullet‐Shaped Magnetite Biomineralization Within a Magnetotactic Deltaproteobacterium: Implications for Magnetofossil Identification

Menguy

Roberts

et al. 2020

JGR Biogeosciences

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“…The morphology of magnetosomes produced by magnetotactic bacteria (MTB) is considered to be speci c to phylum-or class-level lineages (Bazylinski et al 1994;Kopp and Kirschvink 2007;Lefèvre and Bazylinski 2013). Recent studies on rock magnetism and microbiology suggested that bullet-shaped magnetofossils are preferentially found in the oxic-anoxic transition zone (OATZ), which are produced by MTB of Nitrospirae lineage, whereas magnetofossils of hexagonal prisms and octahedra distribute in both above and within the OATZ (Yamazaki et al 2019;Nakano et al submitted). Thus magnetofossil morphology in sediments can be used as a proxy for past chemical conditions (Usui et al 2017;Yamazaki et al submitted).…”

Section: Discussionmentioning

confidence: 99%

“…Biogenic magnetites may play an important role for remanent magnetization acquisition of sediments (Kirschvink 1983;Ouyang et al 2014;Chen et al 2017). In addition, magnetofossil morphology may be a proxy for sediment chemical conditions in the past (Hesse 1994;Yamazaki and Kawahata 1998;Yamazaki et al 2019). Biogenic magnetites also suffer reductive dissolution as magnetic minerals of other origins, and biogenic magnetites are inferred to be lost earlier than others from their ner grain sizes.…”

Section: Introductionmentioning

confidence: 99%

Reductive dissolution of biogenic magnetite

Yamazaki

2020

Preprint

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Reductive dissolution of magnetites is known to occur below the Fe-redox boundary in sediment columns. This study aims to document the detailed processes of biogenic magnetite dissolution. A sediment core taken from the Japan Sea was used for this purpose, in which reductive dissolution of magnetic minerals are known to start at about 1.3 m in depth and mostly complete within an interval of about 0.3 m. Using first-order reversal curve diagrams, preferential dissolution of biogenic magnetites within this interval is estimated from the observation that a narrow peak extending along the coercivity axis (the central ridge), which is indicative of biogenic magnetite, diminishes downcore. Transmission electron microscopy shows that the sediments contain the three morpho-types of magnetofossils: octahedron, hexagonal prism, and bullet shaped. With the progress of reductive dissolution, the proportion of bullet-shaped magnetofossils decreases, whereas that of hexagonal prisms increases. For hexagonal prisms, {111} caps are often etched while {110} side faces are almost intact. These observations can be explained by the differences in resistivity against dissolution among crystal planes of magnetite. A previous study reported that the dissolution rate of (111) planes is higher than that of (110) planes. Hexagonal prisms elongate in the [111] direction and are wrapped with {110} side faces, whereas octahedral and bullet-shaped magnetofossils have larger proportions of surface areas with {111} faces. Magnetosome morphology may reflect preference of inhabiting magnetotactic bacterial lineage for chemical conditions in sediments. One should, however, be cautious for possible alteration of original morphological composition during reductive diagenesis when magnetofossil morphology is used as a paleoenvironmental proxy.

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Coeval Decline of Biological Productivity and Bottom-water Oxygenation in EEP Ocean Recorded by Magnetofossils during the Antarctic Glaciation

Wang

Yang

Gai

et al. 2022

Preprint

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The biological pump and deep-ocean ventilation in eastern equatorial Pacific (EEP) Ocean are thought to play a crucial role in cases of global CO2 change. However, the integral role of these two processes in regulating atmospheric CO2 perturbations over major climate transitions are still unknown. Here, we present the magnetofossil record in EEP sediments from Sites 1333 and 1218 across the Eocene-Oligocene Transition (EOT) when the major ice-sheet was first established on Antarctica. We find that the EEP dust fertilization and bottom-water oxygenation were well co-archived by magnetofossil in characteristics of abundance and morphology, respectively. Our observations show a coeval decline of EEP biological productivity and deep-ocean ventilation during the Antarctic glacial expansion, and suggest that the reduced deep-ocean ventilation contributed to the global CO2 decline across the EOT, whereas the superimposed biological pump action provided a negative (stabilizing) feedback in the meantime.

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Dependence of bacterial magnetosome morphology on chemical conditions in deep-sea sediments

Cited by 31 publications

References 52 publications

Bullet‐Shaped Magnetite Biomineralization Within a Magnetotactic Deltaproteobacterium: Implications for Magnetofossil Identification

Bullet‐Shaped Magnetite Biomineralization Within a Magnetotactic Deltaproteobacterium: Implications for Magnetofossil Identification

Reductive dissolution of biogenic magnetite

Coeval Decline of Biological Productivity and Bottom-water Oxygenation in EEP Ocean Recorded by Magnetofossils during the Antarctic Glaciation

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