A morphological classification of bacteria containing bullet-shaped magnetic particles

Thornhill, Richard; Burgess, J. Grant; Sakaguchi, Toshifumi; Matsunaga, Tadashi

doi:10.1111/j.1574-6968.1994.tb06633.x

Cited by 55 publications

(31 citation statements)

References 29 publications

(31 reference statements)

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“…Since the first peer-reviewed report of magnetotactic bacteria in 1975 (Blakemore 1975), various morphological types including cocci, spirilla, vibrios, ovoid bacteria, rod-shaped bacteria and multicellular bacteria (Thornhill et al 1994;Spring & Schleifer 1995) possessing unique characteristics have been identified and observed to inhabit various aquatic environments. Magnetotactic cocci, for example, have shown high diversity and distribution and have been frequently identified at the surface of aquatic sediments .…”

Section: Diversity Of Magnetotactic Bacteriamentioning

confidence: 99%

Formation of magnetite by bacteria and its application

Arakaki

Nakazawa

Nemoto

et al. 2008

J. R. Soc. Interface.

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220

176

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Magnetic particles offer high technological potential since they can be conveniently collected with an external magnetic field. Magnetotactic bacteria synthesize bacterial magnetic particles (BacMPs) with well-controlled size and morphology. BacMPs are individually covered with thin organic membrane, which confers high and even dispersion in aqueous solutions compared with artificial magnetites, making them ideal biotechnological materials. Recent molecular studies including genome sequence, mutagenesis, gene expression and proteome analyses indicated a number of genes and proteins which play important roles for BacMP biomineralization. Some of the genes and proteins identified from these studies have allowed us to express functional proteins efficiently onto BacMPs, through genetic engineering, permitting the preservation of the protein activity, leading to a simple preparation of functional protein-magnetic particle complexes. They were applicable to high-sensitivity immunoassay, drug screening and cell separation. Furthermore, fully automated single nucleotide polymorphism discrimination and DNA recovery systems have been developed to use these functionalized BacMPs. The nano-sized fine magnetic particles offer vast potential in new nano-techniques.

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Section: Diversity Of Magnetotactic Bacteriamentioning

confidence: 99%

Formation of magnetite by bacteria and its application

Arakaki

Nakazawa

Nemoto

et al. 2008

J. R. Soc. Interface.

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220

176

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“…In addition, bacteria that are morphologically similar to "Ca. Magnetobacterium bavaricum" and other Nitrospirae MTB have also been found in sediments worldwide, including those in Brazil (36), France (18), Japan (52), and the United States (37), but their phylogenetic affiliations have not been identified yet. These results suggest that MTB of the phylum Nitrospirae are likely globally distributed.…”

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confidence: 99%

Newly Isolated but Uncultivated Magnetotactic Bacterium of the Phylum Nitrospirae from Beijing, China

Lin

Pan

2012

Appl Environ Microbiol

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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 lineage with >6% 16S rRNA gene sequence divergence from all currently described MTB. MWB-1 contained 200 to 300 intracellular bullet-shaped magnetite magnetosomes and showed a helical swimming trajectory under homogeneous magnetic fields; its magnetotactic velocity decreased with increasing field strength, and vice versa. A robust phylogenetic framework for MWB-1 and all currently known MTB in the phylum Nitrospirae was constructed utilizing maximumlikelihood and Bayesian algorithms, which yielded strong evidence that the Nitrospirae MTB could be divided into four well-supported groups. Considering its population densities in sediment and its high numbers of magnetosomes, MWB-1 was estimated to account for more than 10% of the natural remanent magnetization of the surface sediment. Taken together, the results of this study suggest that MTB in the phylum Nitrospirae are more diverse than previously realized and can make important contributions to the sedimentary magnetization in particular environments. Biomineralization of magnetic minerals has been discovered in a broad range of organisms, including birds, fishes, mollusks, insects, and microorganisms (23,53,55). A typical example of biomineralization is found in magnetotactic bacteria (MTB), a morphologically and phylogenetically diverse group of microorganisms that form special intracellular organelles, called magnetosomes (3, 5). Magnetosomes are membrane-enveloped, nanosized, high-purity crystals of iron oxide magnetite and/or iron sulfide greigite, usually arranged into one or more linear chains (21). These specific organelles help MTB to sense and swim along the earth's magnetic field, a behavior known as magnetotaxis (8). In conjunction with aerotaxis and chemotaxis, magnetotaxis facilitates the location of MTB to their favorable positions in vertical chemical gradients in the oxic-anoxic transition zone (OATZ) (11,40). The ubiquity and abundance of MTB near the OATZ suggest their potentially important roles in the geochemical cycling of iron and sulfur in nature (48). Molecular approaches based on 16S rRNA gene sequencing have provided evidence for the phylogenetic heterogeneity of MTB. Most discovered MTB are affiliated with the Alphaproteobacteria, but MTB belonging to the Gammaproteobacteria, the Deltaproteobacteria, and Nitrospirae have also been described (2, 28).One of the most intriguing examples of MTB is "Candidatus Magnetobacterium bavaricum," a magnetite-producing MTB within the deep-branching bacterial phylum Nitrospirae that was first discovered in Lake Chiemsee in Upper Bavaria, Germany (49, 54). "Ca. Magnetobacterium bavaricum" is a large, rod-shaped bact...

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“…Although magnetotactic cells are usually found at cell densities of approximately 10 4 to 10 7 cells/cm 3 , these values vary greatly depending on the sampling site (7,26,30). In this study, we examined a sediment sample that contained approximately 1 ϫ 10 5 magnetotactic bacteria per cm 3 , and approximately 10 5 cells were obtained after purification by the racetrack method.…”

Section: Discussionmentioning

confidence: 99%

“…Since the first report on the identification of magnetotactic bacteria (2), the morphological and phylogenetic diversity of these organisms has been observed in various aquatic environments (12,25,27,30). However, bacterial strains available in pure culture are currently limited to a few genera.…”

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confidence: 99%

Preparation of Genomic DNA from a Single Species of Uncultured Magnetotactic Bacterium by Multiple-Displacement Amplification

Arakaki

Shibusawa

Hosokawa

et al. 2010

Appl Environ Microbiol

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Magnetotactic bacteria comprise a phylogenetically diverse group that is capable of synthesizing intracellular magnetic particles. Although various morphotypes of magnetotactic bacteria have been observed in the environment, bacterial strains available in pure culture are currently limited to a few genera due to difficulties in their enrichment and cultivation. In order to obtain genetic information from uncultured magnetotactic bacteria, a genome preparation method that involves magnetic separation of cells, flow cytometry, and multiple displacement amplification (MDA) using 29 polymerase was used in this study. The conditions for the MDA reaction using samples containing 1 to 100 cells were evaluated using a pure-culture magnetotactic bacterium, "Magnetospirillum magneticum AMB-1," whose complete genome sequence is available. Uniform gene amplification was confirmed by quantitative PCR (Q-PCR) when 100 cells were used as a template. This method was then applied for genome preparation of uncultured magnetotactic bacteria from complex bacterial communities in an aquatic environment. A sample containing 100 cells of the uncultured magnetotactic coccus was prepared by magnetic cell separation and flow cytometry and used as an MDA template. 16S rRNA sequence analysis of the MDA product from these 100 cells revealed that the amplified genomic DNA was from a single species of magnetotactic bacterium that was phylogenetically affiliated with magnetotactic cocci in the Alphaproteobacteria. The combined use of magnetic separation, flow cytometry, and MDA provides a new strategy to access individual genetic information from magnetotactic bacteria in environmental samples.

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A morphological classification of bacteria containing bullet-shaped magnetic particles

Cited by 55 publications

References 29 publications

Formation of magnetite by bacteria and its application

Formation of magnetite by bacteria and its application

Newly Isolated but Uncultivated Magnetotactic Bacterium of the Phylum Nitrospirae from Beijing, China

Preparation of Genomic DNA from a Single Species of Uncultured Magnetotactic Bacterium by Multiple-Displacement Amplification

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