The molecular signature of sulfide: Biomarkers of sulfur-oxidizing autotrophs

地球历史上的缺氧环境是激烈研究和争论的主题。低温硫氧化还原梯度是这些古环境的一个特征。在现代环境中，氧化还原梯度中的微生物硫氧化剂是极其多样的，起源于至少7个主要的原核谱系。这些微生物的脂质特征知之甚少，但作为潜在的分子化石（生物标志物）具有极大的兴趣。该项目的目标是寻找低温硫氧化岩石自养生物的脂质组成和生态特征的缺失信息。在这项工作中收集的数据将有意义的古缺氧环境的研究，代表主要的生物和地球化学基准在地球的演化，如最初出现的产氧光合生物，全球氧化的地表地球，新元古代雪球地球事件，二叠纪/三叠纪灭绝，和其他时期的全球海洋缺氧。从光和无光的现代硫化物梯度的样品的研究将建立一个生态和地球化学背景下解释有机生物标志在整个地质记录的硫化物环境。它还将有助于对微生物如何在微生物主导的生态系统中组装的基本生态学理解，例如早期地球上存在的生态系统。该项目支持我们的长期目标，即在环境中丰富的微生物中的脂质化学，脂质合成途径的进化和脂质分子化石的地质记录之间建立更强的联系。指导研究生和本科生是该项目的核心，将支持两个博士学位。学生和6名暑期本科研究生。该项目还将涉及4名机械和电气工程本科生通过宾夕法尼亚州立大学的学习工厂进行高级顶点项目。研究结果将以“地球缓存”的形式向公众传播，这是一种网络组织的地理挑战游戏，传达有关微生物多样性、进化、深层时间、地球化学循环和环境质量的特定地点信息。

EAR0525503Anoxic environments in earth's history are the subject of intense research and debate. Low temperature sulfur redox gradients are a diagnostic feature of these paleoenvironments. Microbial sulfur-oxidizers populating redox gradients in modern environments are extremely diverse, originating in at least 7 major prokaryotic lineages. The lipid signatures of these microorganisms are poorly known, but are of great interest as potential molecular fossils (biomarkers). The proposed project targets missing information about lipid compositions and ecological characteristics of low-temperature sulfur-oxidizing lithoautotrophs. Data gathered in this work will have significance for studies of ancient anoxic environments representing major biological and geochemical benchmarks in earth's evolution such as the initial appearance of oxygen-producing phototrophs, the global oxidation of the surface earth, Neoproterozoic snowball earth events, the Permian/Triassic extinction, and other periods of global ocean anoxia. Study of samples from photic and aphotic modern sulfide gradients will establish an ecological and biogeochemical context for interpreting organic biosignatures in sulfidic environments throughout the geologic record. It will also contribute basic ecological understanding of how microorganisms are assembled in microbially-dominated ecosystems such as those present on the early earth. This project supports our long-term goal of forging stronger links between the chemistry of lipids in microorganisms abundant in the environment, the evolution of lipid synthesis pathways, and the geologic record of lipid molecular fossils. Mentoring of graduate and undergraduate students is at the core of the project, which will support two Ph.D. students and 6 summer undergraduate research students. This project will also involve 4 undergraduate mechanical and electrical engineering undergraduate students doing senior capstone projects via Penn State's Learning Factory. Research results will be communicated to the general public in the form of "Earthcaches", web-organized geographical challenge games that convey site-specific information about microbial diversity, evolution, deep time, biogeochemical cycling, and environmental quality.