Magnetotactic Bacteria from Extreme Environments

Abstract

Magnetotactic bacteria (MTB) represent a diverse collection of motile prokaryotes that biomineralize intracellular, membrane-bounded, tens-of-nanometer-sized crystals of a magnetic mineral called magnetosomes. Magnetosome minerals consist of either magnetite (Fe3O4) or greigite (Fe3S4) and cause cells to align along the Earth’s geomagnetic field lines as they swim, a trait called magnetotaxis. MTB are known to mainly inhabit the oxic–anoxic interface (OAI) in water columns or sediments of aquatic habitats and it is currently thought that magnetosomes function as a means of making chemotaxis more efficient in locating and maintaining an optimal position for growth and survival at the OAI. Known cultured and uncultured MTB are phylogenetically associated with the Alpha-, Gamma- and Deltaproteobacteria classes of the phylum Proteobacteria, the Nitrospirae phylum and the candidate division OP3, part of the Planctomycetes-Verrucomicrobia-Chlamydiae (PVC) bacterial superphylum. MTB are generally thought to be ubiquitous in aquatic environments as they are cosmopolitan in distribution and have been found in every continent although for years MTB were thought to be restricted to habitats with pH values near neutral and at ambient temperature. Recently, however, moderate thermophilic and alkaliphilic MTB have been described including: an uncultured, moderately thermophilic magnetotactic bacterium present in hot springs in northern Nevada with a probable upper growth limit of about 63 °C; and several strains of obligately alkaliphilic MTB isolated in pure culture from different aquatic habitats in California, including the hypersaline, extremely alkaline Mono Lake, with an optimal growth pH of >9.0.

Origin of microbial biomineralization and magnetotaxis during the Archean

“…For example, many extant MTB are chemolithoautotrophic and have the ability to fix CO 2 either via the Calvin-Benson-Bassham cycle, the reverse tricarboxylic acid cycle, or the reductive acetyl-CoA (Wood-Ljungdahl) pathway (1, 17, 18). (36), supporting the possibility of these bacteria surviving in a hot Archean ocean.…”

Life with compass: diversity and biogeography of magnetotactic bacteria

“…Members of MTB occupy a wide array of ecosystems, including lakes, rivers, ponds, estuaries and salt marshes, lagoons, mangrove swamps, intertidal zones, deep‐sea sediments, soils, and even some extreme environments (Fassbinder et al ., ; Petermann and Bleil, ; Flies et al ., 2005a; Simmons et al ., ; Pan et al ., ; Jogler and Schüler, ; Jogler et al ., ; Wenter et al ., ; Sobrinho et al ., ; Lin et al ., 2012c; 2013; Martins et al ., ; Zhang et al ., 2012; 2013; Zhou et al ., 2012; 2013; Bazylinski and Lefèvre, ). So far MTB have been globally detected from Asia, Europe, North and South America, Africa, Australia, and Antarctica (Fig.…”

Novel co-enrichment method for isolation of magnetotactic bacteria

“…MTB can occupy even up to 30% proportion of microbial biomass thereby dominating the sediment ecology [11,12]. So far the presence of viable MTB cells has been demonstrated in variety of ecosystems such as lakes, ponds, salt marshes, soils, deep sea sediments, rivers, estuaries, lagoons, intertidal zones, mangrove swamps, and few unusual extreme environments [2,[13][14][15][16][17][18][19][20][21][22][23][24][25][26]. MTB are known to have a dominant role in iron cycle of aquatic environments [27], they are estimated to contribute 1-10% of total iron flux in marine environments [28].…”