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学、地球化学和生态学的重要性和影响现已得到广泛承认。 直到最近，一个问题一直是个谜，那就是为什么在低pH值的喷口流体中，没有嗜酸生物从这些生态系统中分离出来？ 鉴于最近发现深海特有古细菌谱系的第一个培养成员DHVE 2是一种嗜热嗜酸菌，在pH 4.5时生长最好，在pH 6以上无法生长，本项目的研究人员准备将这种生物作为模式生物，探索深海喷口嗜热嗜酸菌的生态。 此外，这是在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%，其基因组目前正在由文特尔研究所测序。 因此，拟议的研究将进一步加深我们对这一重要的热液喷口古菌谱系的分子生理生态学和生物地理学的理解。 该项目的长期目标是深入了解嗜热酸生物在深海热液喷口生态系统中发挥的作用。 具体目标包括了解从东劳扩散中心、瓜伊马斯盆地和中阿西奇海脊喷口点的烟囱中嗜热嗜酸古菌的空间分布、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嗜酸古菌的出现产生巨大影响，并影响与其他喷口微生物争夺重叠小生境的竞争。 该项目的调查人员预测，在pH值中等（pH值3-5）的深海喷口处，嗜热嗜酸菌的数量将更多，而在喷口流体pH值极端（pH值3、5）的喷口处，嗜热嗜酸菌的数量将较少。 为了完成这项工作，调查人员将从上述三个对比鲜明的深海热液喷口系统收集烟囱样本。 将对在这些地点收集的样品进行各种培养和分子技术，以研究喷口地点之间嗜热酸菌的多样性、它们与其他喷口细菌竞争的能力及其代谢活动。 此外，还将对深海喷口新的嗜热嗜酸菌进行分离和鉴定。 嗜热酸菌独特的生物学特性正被用于生物沥滤/生物采矿应用，深海喷口发现新的嗜热酸菌有可能为这些生物的生物补救和生物技术应用提供工具。 调查人员还参与培训少数民族研究生和高中科学教师。

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.