title: Characterization and phylogenetic identification of a species of spherical multicellular magnetotactic prokaryotes that produces both magnetite and greigite crystals.
abstract: Magnetotactic bacteria (MTB) are a group of Gram-negative bacteria synthesizing magnetic crystals that allow them aligning along magnetic field lines. They have diverse morphologies including cocci, rods, vibrio, spirilla, and multicellular magnetotactic prokaryotes (MMPs). MMPs are composed of 10-57 cells with peritrichous flagella on their outer surfaces and swim as an entire unit. Here, we describe a species of spherical MMPs isolated from intertidal sediments of Lake Yuehu (Yellow Sea, China). They were mainly found in the subsurface layer of gray-black sediments. Microscopy revealed that these spherical MMPs were 5.6 ± 0.9 μm in diameter and composed of approximately 16-32 ovoid cells with a helical arrangement and peritrichous flagellation. High-resolution transmission electron microscopy showed that the MMPs contained both bullet-shaped magnetite and irregular greigite magnetosomes that were arranged in chains or clusters. These MMPs displayed typical escape motility and negative phototaxis. The 16S rRNA genes of micromanipulation-purified spherical MMPs were cloned and sequenced. Phylogenetic analysis revealed that the MMP species was affiliated with Deltaproteobacteria and displayed >2.8% sequence divergence with respect to previously reported MMPs. This is the first phylogenetic identification of a spherical MMP that produces both magnetite and greigite magnetosomes.
authors.affiliation: Key Laboratory of Marine Ecology & Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China; Laboratoire International Associé de la Bio-Minéralisation et Nano-Structures, CNRS, Marseille, France. Electronic address: zhangruihi.cool@163.com.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Marine Ecology & Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China; Laboratoire International Associé de la Bio-Minéralisation et Nano-Structures, CNRS, Marseille, France. Electronic address: chen-yiran@163.com.
authors.forename: Yi-Ran
authors.initials: YR
authors.lastname: Chen
authors.affiliation: Key Laboratory of Marine Ecology & Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China; Laboratoire International Associé de la Bio-Minéralisation et Nano-Structures, CNRS, Marseille, France. Electronic address: dhjconan3000@163.com.
authors.forename: Hai-Jian
authors.initials: HJ
authors.lastname: Du
authors.affiliation: Key Laboratory of Marine Ecology & Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratoire International Associé de la Bio-Minéralisation et Nano-Structures, CNRS, Marseille, France. Electronic address: zhangwy@qdio.ac.cn.
authors.forename: Wen-Yan
authors.initials: WY
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Marine Ecology & Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratoire International Associé de la Bio-Minéralisation et Nano-Structures, CNRS, Marseille, France. Electronic address: panhongmiao@qdio.ac.cn.
authors.forename: Hong-Miao
authors.initials: HM
authors.lastname: Pan
authors.affiliation: Key Laboratory of Marine Ecology & Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratoire International Associé de la Bio-Minéralisation et Nano-Structures, CNRS, Marseille, France. Electronic address: txiao@qdio.ac.cn.
authors.forename: Tian
authors.initials: T
authors.lastname: Xiao
authors.affiliation: Laboratoire de Chimie Bactérienne, UMR7283, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université, CNRS, Marseille, France; Laboratoire International Associé de la Bio-Minéralisation et Nano-Structures, CNRS, Marseille, France. Electronic address: wu@imm.cnrs.fr.
authors.forename: Long-Fei
authors.initials: LF
authors.lastname: Wu
mesh_terms: D002681:China; D016000:Cluster Analysis; D003460:Crystallization; D003593:Cytoplasm / Q000648:ultrastructure; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D020564:Deltaproteobacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D052203:Ferrosoferric Oxide / Q000378:metabolism*; D019015:Geologic Sediments / Q000382:microbiology*; D007501:Iron / Q000378:metabolism*; D008124:Locomotion; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013440:Sulfides / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D013440:Sulfides; C111959:greigite; D007501:Iron; D052203:Ferrosoferric Oxide
keywords: Deltaproteobacteria; Greigite crystals; Intertidal sediments; Magnetite crystals; Spherical MMPs