title: Insight into the evolution of magnetotaxis in Magnetospirillum spp., based on mam gene phylogeny.
abstract: Vibrioid- to helical-shaped magnetotactic bacteria phylogenetically related to the genus Magnetospirillum were isolated in axenic cultures from a number of freshwater and brackish environments located in the southwestern United States. Based on 16S rRNA gene sequences, most of the new isolates represent new Magnetospirillum species or new strains of known Magnetospirillum species, while one isolate appears to represent a new genus basal to Magnetospirillum. Partial sequences of conserved mam genes, genes reported to be involved in the magnetosome and magnetosome chain formation, and form II of the ribulose-1,5-bisphosphate carboxylase/oxygenase gene (cbbM) were determined in the new isolates and compared. The cbbM gene was chosen for comparison because it is not involved in magnetosome synthesis; it is highly conserved and is present in all but possibly one of the genomes of the magnetospirilla and the new isolates. Phylogenies based on 16S rRNA, cbbM, and mam gene sequences were reasonably congruent, indicating that the genes involved in magnetotaxis were acquired by a common ancestor of the Magnetospirillum clade. However, in one case, magnetosome genes might have been acquired through horizontal gene transfer. Our results also extend the known diversity of the Magnetospirillum group and show that they are widespread in freshwater environments.
authors.affiliation: CEA Cadarache/CNRS/Université Aix-Marseille, UMR7265 Service de Biologie Végétale et de Microbiologie Environnementale, Laboratoire de Bioénergétique Cellulaire, Saint Paul lez Durance, France.
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Lefèvre
authors.forename: Marian L
authors.initials: ML
authors.lastname: Schmidt
authors.forename: Nathan
authors.initials: N
authors.lastname: Viloria
authors.forename: Denis
authors.initials: D
authors.lastname: Trubitsyn
authors.forename: Dirk
authors.initials: D
authors.lastname: Schüler
authors.forename: Dennis A
authors.initials: DA
authors.lastname: Bazylinski
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D022761:Gene Transfer, Horizontal; D008124:Locomotion; D008280:Magnetics; D042201:Magnetospirillum / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D015206:Southwestern United States; D014871:Water Microbiology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S