Studies on Physiological Ecology and Genetics of Hydrothermal Vent Sulfur Bacteria

热液喷口硫细菌的生理生态学和遗传学研究

• 批准号: 9018198
• 负责人: Douglas Nelson
• 金额: $ 17.83万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-12-15 至 1994-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9018198&HistoricalAwards=false
• 关键词: Studies; Physiological; Ecology; Genetics; Hydrothermal

Animal communities at the recently discovered deep Sea hydrothermal vents (depth 2000 m) exhibit biomass densities which are probably as high as any ecosystem on earth. As a matter reaches the sea floor at such depths (Suess, 1980). Instead, local production of organic carbon by chemoautotrophic bacteria is believed to form much or all of the nutritional base at these vents. At the vents some of these bacteria are free-living either suspended in hydrothermal plumes or attached to surfaces (Jannasch and Mottl, 1985; Jannasch, 1989). These offer food sources for filter feeding and surface grazing vent animals. In this permanently dark environment, however, the major portion of life-supporting interactions between bacteria and animals occurs in endosymbiotic associations (reviewed by Childress et al., 1987). In most examples studied to date the symbiont is some type of chemoautotrophic sulfur bacterium, but methane oxidizing symbionts are also known (Cavanaugh et al., 1987; Childress et al., 1986). Chemoautotrophic sulfur bacteria generate energy (ATP or a proton motive force) by the oxidation of reduced sulfur compounds (sulfide, elemental sulfur, thiosulfate, etc.) and usually fix CO2 via the Calvin- Benson cycle also employed by green plants and algae, There are two general ways a symbiont might provide nutrients to its host. The symbiont might remain intact but overproduce certain organics which leak out of the symbiont or be deposited extracellularly. Alternatively, the host might degrade a fraction of the bacteria using lytic enzymes, possibly localized in vacuoles. There is little evidence pointing to the operation of either mechanism.

最近发现的深海热液喷口（深度 2000 米）的动物群落的生物量密度可能与地球上任何生态系统一样高。 事实上，物质到达海底的深度如此之大（Suess，1980）。 相反，化学自养细菌局部产生的有机碳被认为形成了这些喷口的大部分或全部营养基础。 在喷口处，其中一些细菌是自由生活的，或者悬浮在热液羽流中，或者附着在表面上（Jannasch 和 Mottl，1985；Jannasch，1989）。 这些为滤食动物和地表放牧动物提供食物来源。 然而，在这种永久黑暗的环境中，细菌和动物之间维持生命的相互作用的主要部分发生在内共生关联中（Childress等人，1987年综述）。 在迄今为止研究的大多数例子中，共生体是某种类型的化学自养硫细菌，但甲烷氧化共生体也是已知的（Cavanaugh 等人，1987；Childress 等人，1986）。 化能自养硫细菌通过还原硫化合物（硫化物、元素硫、硫代硫酸盐等）的氧化产生能量（ATP或质子动力），并且通常通过绿色植物和藻类也采用的卡尔文-本森循环来固定二氧化碳。共生体可以通过两种一般方式为其宿主提供营养。 共生体可能保持完整，但会过度产生某些有机物，这些有机物会从共生体中泄漏出来或沉积在细胞外。 或者，宿主可能使用可能位于液泡中的裂解酶降解一小部分细菌。 几乎没有证据表明这两种机制的运作。