近日，国际期刊Environmental Microbiology发表了中科院海洋研究所肖天研究员课题组与法国科学院吴龙飞教授课题组合作项目的研究成果，他们开展了海洋趋磁微生物多样性及系统进化研究。研究人员在我国黄海潮间带沉积物中发现一种新的多细胞趋磁原核生物——菠萝型多细胞趋磁原核生物（pineapple-like MMPs）。
科研人员通过对该多细胞趋磁原核生物的运动行为、分离繁殖和整体结构等方面进行研究，发现其多细胞性更加显著，通过16S rDNA系统进化分析确定其为一个新种属，定名为Candidatus Magnetananas tsingtaoensis。
趋磁细菌形态多样，有球形、杆形、弧形、螺旋形以及多细胞聚集体等，其中以多细胞聚集体——多细胞趋磁原核生物（multicellular magnetotactic prokaryotes，MMPs）最为特殊。MMPs是一类由多个含磁小体的原核细胞有序排列形成的趋磁生物，在细胞结构、生态分布与分类地位等方面有其特殊性，目前仅在海洋环境发现。科学家对该生物是单细胞形成的聚集体还是多细胞生命体各持己见，其进化位置尚不明确。这一最新发现为多细胞趋磁原核生物进化位置确定提供了新证据。
趋磁细菌（magnetotactic bacteria）是一类可以沿着地磁场方向运动的特殊细菌，其体内含有被磷脂膜包被的单磁畴颗粒——磁小体（magnetosome）。趋磁细菌是探索细胞器官起源、生物矿化及其分子机理，以及研究地磁场对生命影响机制不可替代的模式系统，具有重要的生物学研究意义。同时，磁小体为生物纳米磁性材料在生物医药和材料领域的应用提供了广阔的前景。（生物谷Bioon.com）
doi:10.1111/j.1462-2920.2011.02590.x
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A novel genus of multicellular magnetotactic prokaryotes from the Yellow Sea
Zhou, Ke; Zhang, Wen‐Yan; Yu‐\Zhang, Kui; Pan, Hong‐Miao; Zhang, Sheng‐Da; Zhang, Wei‐Jia; Yue, Hai‐Dong; Li, Ying; Xiao, Tian; Wu, Long‐Fei
Multicellular magnetotactic prokaryotes (MMPs) are a group of magnetotactic microorganisms composed of 10–40 Gram-negative cells. Currently, all the identified MMPs show a spherical morphology and synthesize mainly iron sulfide magnetosomes. In this study, we report a novel genus of MMPs with peculiar ellipsoidal morphology and iron oxide magnetosomes, which were discovered in intertidal sediment of the Yellow Sea in China. Optical and fluorescence microscopy revealed that this organism was ～10 × 8 μm in size and composed of ～40 cells enveloped by an outer layer. Scanning electron microscopy showed that the cells were arranged in 4–6 interlaced circles. Bullet-shaped magnetite magnetosomes were organized in chains roughly parallel to the long axis of the ellipsoidal MMPs when analysed by transmission electron microscopy. These MMPs displayed special escape motility, i.e. swimming rapidly from the edge to the centre of the droplet and then slowly back to the edge. In addition, they exhibited negative phototaxis. Light microscopy observations showed that the ellipsoidal MMPs reproduced by division along the body long axis. Both analysis of 16S rRNA gene sequence and fluorescence in situ hybridization revealed the ellipsoidal MMPs as a new genus of the Deltaproteobacteria. In summary, this novel genus of MMPs exhibit unique morphology, peculiar division process and distinct phylogenetic affiliation compared with the other MMPs.
