EAPSI: Physical characterization of extreme, deep-subsurface microorganisms from Homestake Gold Mine

地球深层是一个典型的极端、能源匮乏的生态系统。这个巨大的生物圈代表着地球上最大的微生物栖息地，其环境与其他行星地下发现的环境相似。该项目旨在培养和描述地球深层大陆地下的微生物生命，特别是在南达科他州的前Homestake矿。最近发现，大陆深层地下是一个种群繁衍的生态系统，单细胞生物体在这里生存。在大陆地下，在地球表面以下3.3公里处发现了微生物生命。实验室中只培养了几种深层地下微生物，因此它们是如何存活的尚不清楚。来自深层地下的生物样本不会使用传统的微生物培养技术生长。因此，成功地培养其居民需要创新的技术。JAMSTEC-Yokosuka的Hiroyuki Imachi博士设计了低流量生物反应器，从地下培养挑剔的、低能量适应的厌氧菌(使用终端电子受体而不是O2的生物体)。在目前的研究中，从Homestake矿地下5000英尺处采集的水和岩石样本将在低流量生物反应器中培养。生物反应器含有矿物基质和介质，旨在模拟采集样本的深层地下环境。随后从反应堆收集的污水产生了丰富的地下厌氧菌，非常适合分离和表征典型的低密度、生长缓慢的微生物。对这些以前未被研究过的微生物进行分类和代谢特征的方法将包括rRNA和功能基因测序、脂质分析、代谢底物的使用以及用于现场环境检测的qPCR和FISH探针设计。由于地球的次表面与其他行星类似，了解地球深层的生命是如何存在的，将有助于在其他行星的次表面寻找生命。该NSF EAPSI奖是与日本科学促进会合作资助的。

Earth's deep subsurface is a typically extreme, energy-starved ecosystem. This vast biosphere represents the largest microbial habitat on Earth and is a similar environment to those found in the subsurface of other planets. This project aims to grow and characterize microbial life in Earth's deep continental subsurface, specifically at the former Homestake Mine, in South Dakota. It was recently discovered that the continental deep subsurface is a populated ecosystem where single-celled organisms survive. In the continental subsurface, microbial life has been detected 3.3 km below Earth's surface. Only a few deep subsurface microorganisms have been grown in the laboratory hence how they survive remains unclear. Biological samples from the deep subsurface will not grow using traditional microbiological cultivation techniques. Therefore, successfully cultivating its residents requires innovative technology. Dr. Hiroyuki Imachi at JAMSTEC-Yokosuka in Japan has designed low-flow bioreactors to cultivate fastidious, low energy-adapted anaerobes (organisms that use a terminal electron acceptor other than O2) from the subsurface. For the current study, water and rock samples collected from 5,000 feet below surface at Homestake Mine will be incubated in low-flow bioreactors. The bioreactors contain mineral substrates and media designed to mimic the deep subsurface environment from which samples were collected. Subsequent collections of effluent from the reactors have yielded enrichments of subsurface anaerobes, excellent for isolation and metabolic characterization of typically low-density, slow-growing microorganisms. The methods to taxonomically and metabolically characterize these previously unstudied microorganisms will include rRNA and functional gene sequencing, lipid analyses, metabolic substrate usage, and qPCR and FISH probe design for in situ environmental detection. Because Earth's subsurface is analogous to that of other planets, understanding how life exists in Earth's deep subsurface will help in the search for life in the subsurface of other planets. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.