Culture-independent characterization of novel psychrophilic magnetotactic cocci from Antarctic marine sediments
Culture-independent characterization of novel psychrophilic magnetotactic cocci from Antarctic marine sediments
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DOI：
10.1111/1462-2920.13388
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发表时间：
2016-12-01
影响因子：
5.1
通讯作者：
Lins, Ulysses
中科院分区：
文献类型：
--
作者：
Abreu, Fernanda;Carolina, Ana;Lins, Ulysses
趋磁细菌（MTB）是一组广泛存在的异质性水生微生物，能够生物矿化纳米尺寸的、膜结合的、磁性的富铁矿物颗粒（称为磁小体）。MTB存在于化学分层的水生沉积物和/或水柱中，具有广泛的盐度、中高温和中性至强碱性的pH值。从非常寒冷的环境中MTB还没有被调查到任何很大的程度，在这里，我们从低温南极海洋地区的MTB的特点。2009年至2013年，在乔治王岛金钟湾（628230 S 588270 W）的9个采样点采集了沉积物样本。从五个网站的样本中含有结核分枝杆菌和这些网站中的两个含有大量的趋磁球菌，使用电子显微镜和分子技术进行了研究。趋磁球菌含有磁小体排列为两个或四个链或作为一个混乱的集群。高分辨率透射电子显微镜和能量色散X射线显微分析的结晶习性和组成的所有磁小体分析是一致的磁铁矿（Fe 3 O 4）与细长的棱柱形晶体。检索到的16 S rRNA基因序列从磁富集趋磁球菌聚类成三个不同的组，隶属于变形菌门的Alphaproteobacteria类。每个系统发育簇的新序列，证实使用荧光原位杂交。磁富集趋磁球菌的宏基因组数据分析揭示了mam基因和MTB特异性假设蛋白编码基因的存在。序列同源性和系统发育分析表明，预测的蛋白质与培养的α-变形菌MTB相关。趋磁球菌存在的沉积物的持续低温（总是低于1摄氏度）表明这些来自南极洲海洋的MTB是嗜冷生物。此外，从南极洲海洋不同地点收集的样品中检索到相似的形态型和16 S基因序列，表明这些新的MTB菌株是南极微生物群的土著成员。
Magnetotactic bacteria (MTB) are a heterogeneous group of ubiquitous aquatic microorganisms capable of biomineralizing nano-sized, membrane-bound, magnetic iron-rich mineral particles called magnetosomes. MTB are found in chemically-stratified aquatic sediments and/or water columns with a wide range of salinities, moderate to high temperatures, and pH varying from neutral to strongly alkaline. MTB from very cold environments have not been investigated to any great degree and here we characterize MTB from the low temperature Antarctic maritime region. Sediment samples were collected at nine sampling sites within Admiralty Bay, King George Island (628230S 588270W) from 2009 to 2013. Samples from five sites contained MTB and those from two of these sites contained large number of magnetotactic cocci that were studied using electron microscopy and molecular techniques. The magnetotactic cocci contained magnetosomes either arranged as two or four chains or as a disorganized cluster. The crystalline habit and composition of all magnetosomes analyzed with high-resolution transmission electron microscopy and energy dispersive X-ray microanalysis were consistent with elongated prismatic crystals of magnetite (Fe3O4). The retrieved 16S rRNA gene sequences from magnetically-enriched magnetotactic cocci clustered into three distinct groups affiliated with the Alphaproteobacteria class of the Proteobacteria. Novel sequences of each phylogenetic cluster were confirmed using fluorescent in situ hybridization. Metagenomic data analysis of magnetically-enriched magnetotactic cocci revealed the presence of mam genes and MTB-specific hypothetical protein coding genes. Sequence homology and phylogenetic analysis indicated that predicted proteins are related to those of cultivated alphaproteobacterial MTB. The consistent and continuous low temperature of the sediment where the magnetotactic cocci are present (always below 1 degrees C) suggests that these MTB from maritime Antarctica are psychrophiles. Moreover, similar morphotypes and 16S gene sequences were retrieved from samples collected from different sites from maritime Antarctica for several years suggesting that these new strains of MTB are indigenous members of Antarctic microbiota.