Ecology, Diversity, and Evolution of Magnetotactic Bacteria

Lefèvre, Christopher T.; Bazylinski, Dennis A.

doi:10.1128/mmbr.00021-13

Cited by 370 publications

(408 citation statements)

References 228 publications

(524 reference statements)

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“…In fact, magnetotactic bacteria from the Nitrospira phylum are typically found in freshwater lakes, lake sediments and hot springs (reviewed by Amann et al, 2007 andLefevre andBazylinski, 2013). Using cryogenic transmission electron microscopy, we have observed long vibrio-shaped cells with intracellular magnetosome-like structures in AMD biofilms (Figure 8).…”

Section: Community Diversitymentioning

confidence: 87%

Community transcriptomics reveals unexpected high microbial diversity in acidophilic biofilm communities

et al. 2014

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A fundamental question in microbial ecology relates to community structure, and how this varies across environment types. It is widely believed that some environments, such as those at very low pH, host simple communities based on the low number of taxa, possibly due to the extreme environmental conditions. However, most analyses of species richness have relied on methods that provide relatively low ribosomal RNA (rRNA) sampling depth. Here we used community transcriptomics to analyze the microbial diversity of natural acid mine drainage biofilms from the Richmond Mine at Iron Mountain, California. Our analyses target deep pools of rRNA gene transcripts recovered from both natural and laboratory-grown biofilms across varying developmental stages. In all, 91.8% of the B254 million Illumina reads mapped to rRNA genes represented in the SILVA database. Up to 159 different taxa, including Bacteria, Archaea and Eukaryotes, were identified. Diversity measures, ordination and hierarchical clustering separate environmental from laboratory-grown biofilms. In part, this is due to the much larger number of rare members in the environmental biofilms. Although Leptospirillum bacteria generally dominate biofilms, we detect a wide variety of other Nitrospira organisms present at very low abundance. Bacteria from the Chloroflexi phylum were also detected. The results indicate that the primary characteristic that has enabled prior extensive cultivation-independent 'omic' analyses is not simplicity but rather the high dominance by a few taxa. We conclude that a much larger variety of organisms than previously thought have adapted to this extreme environment, although only few are selected for at any one time.

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Section: Community Diversitymentioning

confidence: 87%

Community transcriptomics reveals unexpected high microbial diversity in acidophilic biofilm communities

et al. 2014

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“…However, recent cultivation-independent analyses have revealed an unexpected diversity of MTB outside Proteobacteria (Kolinko et al, 2012;Lefèvre and Bazylinski, 2013;Lin et al, 2014). Among them, those belonging to the genus 'Candidatus Magnetobacterium' in the phylum Nitrospirae are of great interest (Garrity and Holt, 2001).…”

Section: Introductionmentioning

confidence: 99%

Genomic insights into the uncultured genus ‘Candidatus Magnetobacterium’ in the phylum Nitrospirae

et al. 2014

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Magnetotactic bacteria (MTB) of the genus 'Candidatus Magnetobacterium' in phylum Nitrospirae are of great interest because of the formation of hundreds of bullet-shaped magnetite magnetosomes in multiple bundles of chains per cell. These bacteria are worldwide distributed in aquatic environments and have important roles in the biogeochemical cycles of iron and sulfur. However, except for a few short genomic fragments, no genome data are available for this ecologically important genus, and little is known about their metabolic capacity owing to the lack of pure cultures. Here we report the first draft genome sequence of 3.42 Mb from an uncultivated strain tentatively named 'Ca. Magnetobacterium casensis' isolated from Lake Miyun, China. The genome sequence indicates an autotrophic lifestyle using the Wood-Ljungdahl pathway for CO 2 fixation, which has not been described in any previously known MTB or Nitrospirae organisms. Pathways involved in the denitrification, sulfur oxidation and sulfate reduction have been predicted, indicating its considerable capacity for adaptation to variable geochemical conditions and roles in local biogeochemical cycles. Moreover, we have identified a complete magnetosome gene island containing mam, mad and a set of novel genes (named as man genes) putatively responsible for the formation of bullet-shaped magnetite magnetosomes and the arrangement of multiple magnetosome chains. This first comprehensive genomic analysis sheds light on the physiology, ecology and biomineralization of the poorly understood 'Ca. Magnetobacterium' genus.

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“…A taxonomically and ecologically diverse group of free-living bacteria are magnetotactic: their cytoplasm contains one or more chains of proteinbound, biomineralized magnetite or greigite ('magnetosomes'), producing a magnetic dipole within the cell (Lefèvre and Bazylinski, 2013). Magnetotactic bacteria can align with the Earth's magnetic field and move along geomagnetic field lines using their flagella.…”

Section: Introductionmentioning

confidence: 99%

“…Magnetotactic bacteria can align with the Earth's magnetic field and move along geomagnetic field lines using their flagella. Many magnetotactic bacteria are chemolithoautotrophic microaerophiles that use magnetotaxis to locate the oxic-anoxic interface (OAI) within sediments, a favorable environment for them due to the proximity of reduced compounds (for example, hydrogen sulfide) and oxygen (Lefèvre and Bazylinski, 2013).…”

Section: Introductionmentioning

confidence: 99%

Magnetosome-containing bacteria living as symbionts of bivalves

et al. 2014

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Bacteria containing magnetosomes (protein-bound nanoparticles of magnetite or greigite) are common to many sedimentary habitats, but have never been found before to live within another organism. Here, we show that octahedral inclusions in the extracellular symbionts of the marine bivalve Thyasira cf. gouldi contain iron, can exhibit magnetic contrast and are most likely magnetosomes. Based on 16S rRNA sequence analysis, T. cf. gouldi symbionts group with symbiotic and free-living sulfur-oxidizing, chemolithoautotrophic gammaproteobacteria, including the symbionts of other thyasirids. T. cf. gouldi symbionts occur both among the microvilli of gill epithelial cells and in sediments surrounding the bivalves, and are therefore facultative. We propose that free-living T. cf. gouldi symbionts use magnetotaxis as a means of locating the oxic-anoxic interface, an optimal microhabitat for chemolithoautotrophy. T. cf. gouldi could acquire their symbionts from near-burrow sediments (where oxic-anoxic interfaces likely develop due to the host's bioirrigating behavior) using their superextensile feet, which could transfer symbionts to gill surfaces upon retraction into the mantle cavity. Once associated with their host, however, symbionts need not maintain structures for magnetotaxis as the host makes oxygen and reduced sulfur available via bioirrigation and sulfur-mining behaviors. Indeed, we show that within the host, symbionts lose the integrity of their magnetosome chain (and possibly their flagellum). Symbionts are eventually endocytosed and digested in host epithelial cells, and magnetosomes accumulate in host cytoplasm. Both host and symbiont behaviors appear important to symbiosis establishment in thyasirids.

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Ecology, Diversity, and Evolution of Magnetotactic Bacteria

Cited by 370 publications

References 228 publications

Community transcriptomics reveals unexpected high microbial diversity in acidophilic biofilm communities

Community transcriptomics reveals unexpected high microbial diversity in acidophilic biofilm communities

Genomic insights into the uncultured genus ‘Candidatus Magnetobacterium’ in the phylum Nitrospirae

Magnetosome-containing bacteria living as symbionts of bivalves

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