Vertical Migration in the Sediment-Dwelling Sulfur Bacteria Thioploca spp. in Overcoming Diffusion Limitations
Vertical Migration in the Sediment-Dwelling Sulfur Bacteria Thioploca spp. in Overcoming Diffusion Limitations
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沉积物中硫细菌 Thioploca spp 的垂直迁移。
DOI：
10.1128/aem.62.6.1863-1872.1996
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发表时间：
1996
影响因子：
4.4
通讯作者：
Henrik Fossing
中科院分区：
文献类型：
--
作者：
M. Huettel;Stefan Forster;Susanne Klöser;Henrik Fossing
为了研究丝状硫细菌Thioploca spp.的环境需求，我们测试了这些沉积微生物对氧、硝酸盐和硫化物浓度变化的趋化反应。沉积物芯与Thioploca垫，检索从智利大陆架上的氧气最小区，在循环水槽中孵育。此外，25（mu）摩尔的硝酸盐每升的海水流诱导上升的Thioploca毛状体（长度，高达70毫米）在其主要垂直取向的凝胶鞘。丝状体的上端穿透沉积物表面，并在向下游弯曲之前向流动的水中突出1至3 mm。通过穿透扩散边界层，Thioploca spp。促进在长达30 mm的暴露的毛状体部分中有效的硝酸盐吸收。每平方厘米沉积物表面暴露的丝状体的累积长度高达92 cm，总暴露的毛状体表面积为1 cm（sup 2）。对硝酸盐的正反应推翻了对氧的负反应，表明硝酸盐是Thioploca spp使用的主要电子受体。在缺氧的环境中，10倍的硝酸盐通量增加后，大量出现的细丝加强了这一假设。一个积极的趋化反应的硫化物浓度小于100（mu）摩尔升（sup-1）抵消了吸引硝酸盐和，沿着与憎氧反应和较高的硫化物浓度，控制的毛状体的垂直运动。我们认为，成功的Thioploca spp。智利大陆架上的生物是基于这些生物在富含硝酸盐的边界层和硫化物沉积层之间穿梭的能力。
In order to investigate the environmental requirements of the filamentous sulfur bacteria Thioploca spp., we tested the chemotactic responses of these sedimentary microorganisms to changes in oxygen, nitrate, and sulfide concentrations. A sediment core with a Thioploca mat, retrieved from the oxygen-minimum zone on the Chilean shelf, was incubated in a recirculating flume. The addition of 25 (mu)mol of nitrate per liter to the seawater flow induced the ascent of the Thioploca trichomes (length, up to 70 mm) in their mostly vertically oriented gelatinous sheaths. The upper ends of the filaments penetrated the sediment surface and protruded 1 to 3 mm into the flowing water before they bent downstream. By penetrating the diffusive boundary layer, Thioploca spp. facilitate efficient nitrate uptake in exposed trichome sections that are up to 30 mm long. The cumulative length of exposed filaments per square centimeter of sediment surface was up to 92 cm, with a total exposed trichome surface area of 1 cm(sup2). The positive reaction to nitrate overruled a negative response to oxygen, indicating that nitrate is the principal electron acceptor used by Thioploca spp. in the anoxic environment; 10-fold increases in nitrate fluxes after massive emergence of filaments strengthened this hypothesis. A positive chemotactic response to sulfide concentrations of less than 100 (mu)mol liter(sup-1) counteracted the attraction to nitrate and, along with phobic reactions to oxygen and higher sulfide concentrations, controlled the vertical movement of the trichomes. We suggest that the success of Thioploca spp. on the Chilean shelf is based on the ability of these organisms to shuttle between the nitrate-rich boundary layer and the sulfidic sediment strata.