Magnetovibrio blakemorei gen. nov., sp. nov., a magnetotactic bacterium ( Alphaproteobacteria : Rhodospirillaceae ) isolated from a salt marsh

Abstract

A magnetotactic bacterium, designated strain MV-1T, was isolated from sulfide-rich sediments in a salt marsh near Boston, MA, USA. Cells of strain MV-1T were Gram-negative, and vibrioid to helicoid in morphology. Cells were motile by means of a single polar flagellum. The cells appeared to display a transitional state between axial and polar magnetotaxis: cells swam in both directions, but generally had longer excursions in one direction than the other. Cells possessed a single chain of magnetosomes containing truncated hexaoctahedral crystals of magnetite, positioned along the long axis of the cell. Strain MV-1T was a microaerophile that was also capable of anaerobic growth on some nitrogen oxides. Salinities greater than 10 % seawater were required for growth. Strain MV-1T exhibited chemolithoautotrophic growth on thiosulfate and sulfide with oxygen as the terminal electron acceptor (microaerobic growth) and on thiosulfate using nitrous oxide (N2O) as the terminal electron acceptor (anaerobic growth). Chemo-organoautotrophic and methylotrophic growth was supported by formate under microaerobic conditions. Autotrophic growth occurred via the Calvin–Benson–Bassham cycle. Chemo-organoheterotrophic growth was supported by various organic acids and amino acids, under microaerobic and anaerobic conditions. Optimal growth occurred at pH 7.0 and 26–28 °C. The genome of strain MV-1T consisted of a single, circular chromosome, about 3.7 Mb in size, with a G+C content of 52.9–53.5 mol%.Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain MV-1T belongs to the family Rhodospirillaceae within the Alphaproteobacteria , but is not closely related to the genus Magnetospirillum . The name Magnetovibrio blakemorei gen. nov., sp. nov. is proposed for strain MV-1T. The type strain of Magnetovibrio blakemorei is MV-1T ( = ATCC BAA-1436T = DSM 18854T).

Ecology, Diversity, and Evolution of Magnetotactic Bacteria

“…However, in general, this representation of diversity should not be assumed when using various magnetic separation techniques, considering the very diverse swimming speeds of different MTB. Lastly, we have also used the magnetic capillary racetrack technique to separate and purify MTB from enrichment cultures containing nonmagnetotactic contaminants or contaminated cultures of known MTB (38). Limitations of the magnetic capillary racetrack can be circumvented by the application of single-cellsorting techniques by which any conspicuous morphotype of MTB can be targeted and separated from mixed environmental communities of MTB (30,39,40).…”

“…Many magnetite-producing MTB are chemoorganoheterotrophic but facultatively chemolithoautotrophic (38,48,51,52) or are obligately chemolithoautotrophic (53). One species exhibits chemoorganoautotrophic growth, oxidizing formate microaerobically as an electron donor and fixing the product, CO 2 , by using the Calvin-Benson-Bassham (CBB) cycle (38).…”

“…The best-known electron donors for chemolithoautotrophic growth of MTB in this medium are sulfide and thiosulfate (11). For chemoorganoheterotrophic growth, the most effective choices appear to be organic acids (e.g., succinate and acetate) and some amino acids, as no MTB have been shown to utilize any other type of organic compound (e.g., carbohydrates) as a carbon source (38,48,52,54,55).…”

“…One species exhibits chemoorganoautotrophic growth, oxidizing formate microaerobically as an electron donor and fixing the product, CO 2 , by using the Calvin-Benson-Bassham (CBB) cycle (38). Semisolid oxygen concentration gradient medium can be used for both chemolithoautotrophic and chemoorganoheterotrophic growth.…”

Intra-Field Variation of Prokaryotic Communities On and Below the Seafloor in the Back-Arc Hydrothermal System of the Southern Mariana Trough

“…24.1c). One of the closest cultured species for the clones in the Rhodospirillaceae was a magnetotactic bacterium Magnetovibrio blakemorei with 92 % similarity (Bazylinski et al 2013). The physiology of the uncultured bacteria in Hyphomicrobiaceae and Rhodospirillaceae was unclear; however, considering the sample types (i.e., sulfide chimneys, iron-rich mats and rocks on the seafloor) where they were detected, their presence was probably related to the presence of iron and/or sulfide minerals (such as goethite, pyrite, chalcopyrite and sphalerite (Ikehata et al Chap.…”