近日，國(guó)際期刊Environmental Microbiology發(fā)表了中科院海洋研究所肖天研究員課題組與法國(guó)科學(xué)院吳龍飛教授課題組合作項(xiàng)目的研究成果，他們開展了海洋趨磁微生物多樣性及系統(tǒng)進(jìn)化研究,。研究人員在我國(guó)黃海潮間帶沉積物中發(fā)現(xiàn)一種新的多細(xì)胞趨磁原核生物——菠蘿型多細(xì)胞趨磁原核生物（pineapple-like MMPs）。
科研人員通過(guò)對(duì)該多細(xì)胞趨磁原核生物的運(yùn)動(dòng)行為,、分離繁殖和整體結(jié)構(gòu)等方面進(jìn)行研究,，發(fā)現(xiàn)其多細(xì)胞性更加顯著，通過(guò)16S rDNA系統(tǒng)進(jìn)化分析確定其為一個(gè)新種屬,，定名為Candidatus Magnetananas tsingtaoensis,。
趨磁細(xì)菌形態(tài)多樣，有球形,、桿形,、弧形、螺旋形以及多細(xì)胞聚集體等,，其中以多細(xì)胞聚集體——多細(xì)胞趨磁原核生物（multicellular magnetotactic prokaryotes,，MMPs）最為特殊。MMPs是一類由多個(gè)含磁小體的原核細(xì)胞有序排列形成的趨磁生物,，在細(xì)胞結(jié)構(gòu),、生態(tài)分布與分類地位等方面有其特殊性，目前僅在海洋環(huán)境發(fā)現(xiàn),?？茖W(xué)家對(duì)該生物是單細(xì)胞形成的聚集體還是多細(xì)胞生命體各持己見，其進(jìn)化位置尚不明確,。這一最新發(fā)現(xiàn)為多細(xì)胞趨磁原核生物進(jìn)化位置確定提供了新證據(jù),。
趨磁細(xì)菌（magnetotactic bacteria）是一類可以沿著地磁場(chǎng)方向運(yùn)動(dòng)的特殊細(xì)菌，其體內(nèi)含有被磷脂膜包被的單磁疇顆粒——磁小體（magnetosome）,。趨磁細(xì)菌是探索細(xì)胞器官起源,、生物礦化及其分子機(jī)理，以及研究地磁場(chǎng)對(duì)生命影響機(jī)制不可替代的模式系統(tǒng),，具有重要的生物學(xué)研究意義,。同時(shí)，磁小體為生物納米磁性材料在生物醫(yī)藥和材料領(lǐng)域的應(yīng)用提供了廣闊的前景,。（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.
