Diversity and distribution of thermoacidophiles at deep-sea hydrothermal vents

微生物活动对热液喷口生态系统的地质、地球化学和生态学的重要性和影响已得到充分认识。直到最近，有一个方面一直是一个谜，那就是——为什么在低排气流体pH值的情况下，没有从这些生态系统中分离出嗜酸菌？鉴于最近发现深海特有古细菌谱系的第一个培养成员DHVE2是一种嗜热酸菌，在pH为4.5时生长最好，在pH高于6时无法生长，该项目的研究人员准备将该生物作为模式生物来探索深海喷口的嗜热酸菌生态。此外，这是许多分子分类学研究中发现的最丰富的古菌谱系，占古菌群落的15%，目前文特尔研究所正在对其基因组进行测序。因此，本研究将进一步加深我们对这一重要古细菌谱系的分子生理生态学和生物地理学的认识。该项目的长期目标是深入了解热嗜酸菌在深海热液喷口生态系统中的作用。具体目标包括了解东劳扩张中心、瓜伊马斯盆地和大西洋中脊喷口遗址烟囱中嗜热酸古菌的空间分布、相对丰度和共生模式，并研究这些地点的喷口化学，因为它们可能对嗜热酸菌的发生产生巨大影响，并影响与其他喷口微生物争夺重叠生态位的竞争。该项目的研究人员预测，在中等pH值（pH 3-5）的深海喷口位置，热嗜酸菌的数量会更多，而在极端喷口流体pH （pH 3-5）的位置，它们的数量会更少。为了完成这项工作，研究人员将从上述三个不同的深海热液喷口系统中收集烟囱样本。将对在这些地点收集的样品进行各种培养和分子技术，以观察热嗜酸菌在喷口位置之间的多样性，它们与其他喷口细菌竞争的能力以及它们的代谢活动。此外，还将从深海喷口分离和鉴定新的嗜热酸菌。嗜热酸菌独特的生物学特性正被用于生物浸出/生物矿化应用，从深海喷口发现新的嗜热酸菌有可能为这些生物的生物修复和生物技术应用提供工具。调查人员还参与了少数民族研究生和高中科学教师的培训。

The importance and impact that microbial activity has on the geology, geochemistry and ecology of hydrothermal vent ecosystems is now well-recognized. One aspect that has until recently been a puzzle, is --why with the low vent fluid pH had no acidophiles been isolated from these ecosystems? Given the recent discovery that the first cultured member of the deep-sea endemic archeael lineage, DHVE2, is a thermoacidophile, growing best at pH 4.5 and unable to grow above pH 6, the investigators in this project are poised to use this organism as a model organism to explore the ecology of thermoacidophiles at deep-sea vents. Furthermore, this is the most abundant archaeal lineage detected in many molecular taxonomy studies, representing up to 15% of the archaeal community, and its genome is currently being sequenced by the Venter Institute. Therefore, the proposed study will further our understanding of the molecular physiological ecology and biogeography of this important archaeal lineage at hydrothermal vents. The long-term objective of this project is to provide insights into the role that thermoacidophiles play in deep-sea hydrothermal vent ecosystems. Specific objectives include understanding the spatial distribution, relative abundance and co-occurrence patterns of thermoacidophilic archaea in chimneys from the Eastern Lau Spreading Center, Guaymas Basin and Mid-Atlanic Ridge vent sites, and to examine the vent chemistries at these sites as they could have dramatic effects on the occurrence of thermoacidophiles and affect the competition for overlapping niches with other vent microbes. The investigators in this project are predicting that thermoacidophiles will be more abundant at deep-sea vent sites of intermediate pH (pH 3-5), whereas they will be less abundant in sites with extreme vent fluid pH (pH 3, 5). To accomplish this work the investigators will collect chimney samples from the three contrasting deep-sea hydrothermal vent systems named above. A variety of cultivation and molecular techniques will be conducted on samples collected at these locations to look at the diversity of thermoacidophiles between vent sites, their ability to compete with other vent bacteria, and their metabolic activity. Additionally, new thermoacidophiles from deep-sea vents will be isolated and characterized. The unique biology of thermoacidophiles is being used in bioleaching/biomining applications and the discovery of new thermoacidophiles from deep-sea vents has the potential to provide tools for bioremediation and biotechnological applications by these organisms. The investigators are also involved in the training of minority graduate students and high school science teachers.