title: Combined genomic and structural analyses of a cultured magnetotactic bacterium reveals its niche adaptation to a dynamic environment.
abstract: Magnetotactic bacteria (MTB) are a unique group of prokaryotes that have a potentially high impact on global geochemical cycling of significant primary elements because of their metabolic plasticity and the ability to biomineralize iron-rich magnetic particles called magnetosomes. Understanding the genetic composition of the few cultivated MTB along with the unique morphological features of this group of bacteria may provide an important framework for discerning their potential biogeochemical roles in natural environments.
  
  
  
  Genomic and ultrastructural analyses were combined to characterize the cultivated magnetotactic coccus Magnetofaba australis strain IT-1. Cells of this species synthesize a single chain of elongated, cuboctahedral magnetite (Fe3O4) magnetosomes that cause them to align along magnetic field lines while they swim being propelled by two bundles of flagella at velocities up to 300 μm s-1. High-speed microscopy imaging showed the cells move in a straight line rather than in the helical trajectory described for other magnetotactic cocci. Specific genes within the genome of Mf. australis strain IT-1 suggest the strain is capable of nitrogen fixation, sulfur reduction and oxidation, synthesis of intracellular polyphosphate granules and transporting iron with low and high affinity. Mf. australis strain IT-1 and Magnetococcus marinus strain MC-1 are closely related phylogenetically although similarity values between their homologous proteins are not very high.
  
  
  
  Mf. australis strain IT-1 inhabits a constantly changing environment and its complete genome sequence reveals a great metabolic plasticity to deal with these changes. Aside from its chemoautotrophic and chemoheterotrophic metabolism, genomic data indicate the cells are capable of nitrogen fixation, possess high and low affinity iron transporters, and might be capable of reducing and oxidizing a number of sulfur compounds. The relatively large number of genes encoding transporters as well as chemotaxis receptors in the genome of Mf. australis strain IT-1 combined with its rapid swimming velocities, indicate that cells respond rapidly to environmental changes.
authors: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941-902, Rio de Janeiro, RJ, Brazil.|Current institution: Departamento de Biologia, Universidade Federal de São Carlos, 18052-780, Sorocaba, SP, Brazil.
authors: Ana Carolina Vieira
authors: AC
authors: Araujo
authors: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941-902, Rio de Janeiro, RJ, Brazil.|School of Life Sciences, University of Nevada at Las Vegas, Las Vegas, NV, 89154-4004, USA.
authors: Viviana
authors: V
authors: Morillo
authors: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941-902, Rio de Janeiro, RJ, Brazil.
authors: Jefferson
authors: J
authors: Cypriano
authors: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941-902, Rio de Janeiro, RJ, Brazil.
authors: Lia Cardoso Rocha Saraiva
authors: LC
authors: Teixeira
authors: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941-902, Rio de Janeiro, RJ, Brazil.
authors: Pedro
authors: P
authors: Leão
authors: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941-902, Rio de Janeiro, RJ, Brazil.
authors: Sidcley
authors: S
authors: Lyra
authors: Departamento de Matemática Aplicada e Computacional, Laboratório Nacional de Computação Científica, 25651-070, Petrópolis, RJ, Brazil.
authors: Luiz Gonzaga de
authors: LG
authors: Almeida
authors: School of Life Sciences, University of Nevada at Las Vegas, Las Vegas, NV, 89154-4004, USA.
authors: Dennis A
authors: DA
authors: Bazylinski
authors: Departamento de Matemática Aplicada e Computacional, Laboratório Nacional de Computação Científica, 25651-070, Petrópolis, RJ, Brazil.
authors: Ana Tereza
authors: AT
authors: Ribeiro de Vasconcelos
authors: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941-902, Rio de Janeiro, RJ, Brazil.
authors: Fernanda
authors: F
authors: Abreu
authors: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941-902, Rio de Janeiro, RJ, Brazil. ulins@micro.ufrj.br.
authors: Ulysses
authors: U
authors: Lins
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D020561:Alphaproteobacteria / Q000166:cytology / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D004777:Environment; D023281:Genomics; D055944:Magnetosomes / Q000378:metabolism; D008903:Minerals / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D008903:Minerals; D017382:Reactive Oxygen Species
keywords: Biomineralization; Genome; Magnetofaba australis strain IT-1; Magnetosome; Magnetotactic bacteria; mam genes