Ultrastructure, tactic behaviour and potential for sulfate reduction of a novel multicellular magnetotactic prokaryote from North Sea sediments.
Ultrastructure, tactic behaviour and potential for sulfate reduction of a novel multicellular magnetotactic prokaryote from North Sea sediments.
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DOI：
10.1111/j.1462-2920.2009.01877.x
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发表时间：
2009-06
影响因子：
5.1
通讯作者：
Roland Wenter;G. Wanner;D. Schüler;J. Overmann
中科院分区：
文献类型：
--
作者：
Roland Wenter;G. Wanner;D. Schüler;J. Overmann
多细胞趋磁原核生物 (MMP) 代表 10-40 个含有磁小体的细菌细胞的高度组织化、球形和可运动的聚集体。尽管 MMP 由不同的细胞组成，每个细胞都有自己的磁小体和鞭毛，但 MMP 在磁场中自行定向并表现出趋磁性。迄今为止，仅在北美和南美的几个沿海泻湖和盐沼中发现了 MMP。在本研究中，在北海沿海潮汐沙滩中发现了一种新型 MMP。高分辨率扫描电子显微镜揭示了子弹形磁小体的存在，这些磁小体以多个平行链排列。在每个聚集体中，单个细胞的磁小体链以相同的方向定向。能量色散X射线（EDX）分析表明磁小体由硫化铁组成。磁小体的这种特殊形态和排列此前尚未在其他 MMP 中报道过。 16S rRNA 基因序列分析揭示了一个单一的系统发育型，它代表了一个新的系统发育谱系，与之前描述的所有 MMP 序列具有 > 或 = 4% 的序列差异，并且与 Deltaproteobacteria 亚门 Desulfobacteraceae 家族中的异化硫酸盐还原性 Desulfosarcina variabilis 相关。特定寡核苷酸探针的荧光原位杂交表明，所研究的潮滩沉积物中的所有 MMP 都属于新的系统发育型。在每个 MMP 中，所有细菌细胞都显示出杂交信号，表明聚集体由相同系统型的细胞组成。在纯化的 MMP 样品中可以检测到异化亚硫酸盐还原酶 (dsrAB) 和异化腺苷 5'-磷酸还原酶 (aprA) 基因，表明 MMP 能够还原硫酸盐。对 41 种不同的测试化合物进行的趋化性测定对乙酸盐和丙酸盐产生了强烈的反应，而其他有机酸、醇、糖、糖醇或硫化物则没有引起任何反应。通过其协调的趋磁性和趋化性，新型MMP很好地适应了潮间带海洋沉积物特有的陡峭化学梯度。
Multicellular magnetotactic prokaryotes (MMPs) represent highly organized, spherical and motile aggregates of 10-40 bacterial cells containing magnetosomes. Although consisting of different cells, each with its own magnetosomes and flagellation, MMPs orient themselves within a magnetic field and exhibit magnetotaxis. So far, MMPs have only been found in several North and South American coastal lagoons and salt marshes. In the present study, a novel type of MMP was discovered in coastal tidal sand flats of the North Sea. High-resolution scanning electron microscopy revealed the presence of bullet-shaped magnetosomes which were aligned in several parallel chains. Within each aggregate, the magnetosome chains of individual cells were oriented in the same direction. Energy dispersive X-ray (EDX) analysis showed that the magnetosomes are composed of iron sulfide. This particular morphology and arrangement of magnetosomes has previously not been reported for other MMPs. 16S rRNA gene sequence analysis revealed a single phylotype which represented a novel phylogenetic lineage with >or= 4% sequence divergence to all previously described MMP sequences and was related to the dissimilatory sulfate-reducing Desulfosarcina variabilis within the family Desulfobacteraceae of the subphylum Deltaproteobacteria. Fluorescence in situ hybridization with a specific oligonucleotide probe revealed that all MMPs in the tidal flat sediments studied belonged to the novel phylotype. Within each MMP, all bacterial cells showed a hybridization signal, indicating that the aggregates are composed of cells of the same phylotype. Genes for dissimilatory sulfite reductase (dsrAB) and dissimilatory adenosine-5'-phosphate reductase (aprA) could be detected in purified MMP samples, suggesting that MMPs are capable of sulfate reduction. Chemotaxis assays with 41 different test compounds yielded strong responses towards acetate and propionate, whereas other organic acids, alcohols, sugars, sugar alcohols or sulfide did not elicit any response. By means of its coordinated magnetotaxis and chemotaxis, the novel type of MMP is well adapted to the steep chemical gradients which are characteristic for intertidal marine sediments.