Ecophysiology and Phylogeny of Diverse Beggiatoa Species, Bacterial Specialists of the Sulfide-Oxygen Interface

不同 Beggiatoa 物种的生态生理学和系统发育，硫化物-氧界面的细菌专家

• 批准号: 9513962
• 负责人: Douglas Nelson
• 金额: $ 23.78万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-03-01 至 2000-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9513962&HistoricalAwards=false
• 关键词: Ecophysiology; Phylogeny; Diverse; Beggiatoa; Species

9513962 Nelson The surfaces of a variety of marine sediments are dominated by colorless sulfur bacteria of the genera Thioploca and Beggiatoa. Although few of these bacteria have been grown in pure culture, the best characterized representatives can multiply at the oxic-anoxic interface where there are steep gradients of hydrogen sulfide and oxygen, which can serve as their oxidizable substrate and oxidant, respectively. There is emerging evidence that these bacteria are also autotrophs, i.e. they can synthesize their cell material starting with carbon dioxide as their sole carbon source. In some environments with little or no available oxygen, the dominant representatives of these bacteria are extremely large and they contain a membrane-bound central vacuole, comprising roughly 80% of cell volume. These are the only bacteria for which this structure has been reported. In dense samples from three different locations, vacuolate Beggiatoa and Thioploca were very recently demonstrated to contain nitrate in concentrations 10,000-fold higher than in their surrounding habitat. This proposal postulates that these bacteria use this internal nitrate as a terminal electron acceptor facilitating their respiration of soluble sulfide and/or organic compounds. Proposed studies include microelectrode and chemical gradient analysis of in situ consumption rates of potential electron donors (sulfide and organics) and electron acceptors (nitrate and oxygen). Assays of diagnostic enzymes and studies using radiolabelled organic and inorganic carbon compounds will help elucidate the relative roles of these compounds in their metabolism. Studies of the time-course of utilization of internal nitrate and the resultant products, coupled with various enzyme assays, will measure the capacity these bacteria have for denitrification. Additionally, using pure cultures in spatially structured cultu re media the relative rates by which these bacteria use organic and inorganic energy and carbon sources sill be assessed. Vacuolate Beggiatoa are proposed as a model of an important link between the vigorous sulfur cycle of eutrophic marine sediments and the nitrogen cycle. If they and Thioploca prove to be denitrifiers, they will be the first example of an ecologically dominant bacterium capable of removing combined nitrogen from a marine ecosystem.

小行星9513962纳尔逊 各种海洋沉积物的表面主要是无色硫细菌属和贝氏菌属。 虽然这些细菌中很少有在纯培养中生长的，但最具特征的代表可以在有陡峭的硫化氢和氧气梯度的缺氧-缺氧界面处繁殖，硫化氢和氧气可以分别作为它们的可氧化底物和氧化剂。 有 新兴 有证据表明这些细菌 是 还有自养生物，即它们可以以二氧化碳作为它们唯一的碳源开始合成它们的细胞材料。 在一些环境中，很少或没有可用的氧气，这些细菌的主要代表是非常大的，它们含有一个膜结合的中央液泡，约占细胞体积的80%。这是唯一一种被报道具有这种结构的细菌。 在来自三个不同地点的密集样本中，空泡状的Beggiatoa和Thioploca最近被证明含有硝酸盐浓度比周围栖息地高10，000倍。 该提议假定这些细菌使用这种内部硝酸盐作为末端电子受体，促进它们对可溶性硫化物和/或有机化合物的呼吸。 建议的研究包括微电极和化学梯度分析的潜在的电子供体（硫化物和有机物）和电子受体（硝酸盐和氧）的原位消耗率。 对诊断酶的测定和使用放射性标记的有机和无机碳化合物的研究将有助于阐明这些化合物在其代谢中的相对作用。 研究利用内部硝酸盐的时间过程和所产生的产品，再加上各种酶的测定，将测量这些细菌的反硝化能力。 此外，在空间结构培养基中使用纯培养物，这些细菌使用有机和无机能量和碳源的相对速率仍有待评估。建议将Benggiatoa作为富营养化海洋沉积物硫循环和氮循环之间的重要联系的模式。 如果他们和硫普罗卡证明 到 他们将是第一批 示例 能够从海洋生态系统中去除化合氮的生态优势细菌。