Simmons Sheri L, Bazylinski Dennis A, Edwards Katrina J
MIT-WHOI Joint Program in Oceanography, MS 52, WHOI, Woods Hole, MA 02543, USA.
Environ Microbiol. 2007 Sep;9(9):2162-74. doi: 10.1111/j.1462-2920.2007.01330.x.
Magnetotactic bacteria (MTB) contain membrane-bound magnetic iron minerals and are globally abundant in the suboxic/anoxic portions of chemically stratified marine and freshwater environments. However, their population dynamics and potential quantitative contribution to the biogeochemical cycles that they influence (iron, sulfur, carbon) have not been previously considered. Here we report the first quantitative description of the distribution of individual species of magnetite- and greigite-producing MTB in a natural system. We developed a quantitative polymerase chain reaction assay targeting 16s rRNA genes to enumerate four major groups of marine MTB, and applied the assay to samples collected with respect to geochemical parameters during summer 2003 in seasonally stratified Salt Pond, MA. Using catalysed reporter deposition-fluorescent in situ hybridization, we also show that a large greigite-producing bacterium is distantly related to Thiomicrospira pelophila in the Gammaproteobacteria. Ribosomal RNA copy numbers obtained with quantitative polymerase chain reaction indicate that MTB comprise up to 10% of total Bacteria and that each organism has a characteristic distributional profile with respect to the chemocline.
趋磁细菌（MTB）含有膜结合的磁性铁矿物，在全球化学分层的海洋和淡水环境的亚oxic/缺氧部分大量存在。然而，它们的种群动态以及对它们所影响的生物地球化学循环（铁、硫、碳）的潜在定量贡献此前尚未得到考虑。在这里，我们报告了自然系统中产生磁铁矿和硫复铁矿的MTB各物种分布的首次定量描述。我们开发了一种针对16s rRNA基因的定量聚合酶链反应检测方法，以枚举海洋MTB的四个主要类群，并将该检测方法应用于2003年夏季在马萨诸塞州季节性分层的盐沼中根据地球化学参数采集的样本。使用催化报告沉积 - 荧光原位杂交技术，我们还表明，一种产生大量硫复铁矿的细菌与γ - 变形菌纲中的嗜硫微螺菌亲缘关系较远。通过定量聚合酶链反应获得的核糖体RNA拷贝数表明，MTB占细菌总数的比例高达10%，并且每种生物在化学跃层方面都有其特征性的分布模式。
