Investigating the Biological Function of Sterols and Hopanoids in Methylococcus capsulatus

生命的大部分历史都是由微生物主导的，它们的代谢发明极大地改变了地球表面的环境，反过来又影响了地球上生命的进化。然而，我们在地球遥远过去的背景下研究微生物生命的能力仍然是一项艰巨的挑战，主要是因为微生物不容易留下诊断形态化石。克服这一挑战的主要策略之一是使用“分子化石”。这种方法将古代岩石中保存的脂质与现代细菌中它们的产生联系起来。作为强有力的地质生物标记物出现的两组脂质是主要由真核生物产生的甾醇和仅由细菌产生的类甾醇类hopanoids。在本项目中，研究者将研究这两种脂质在荚膜甲基球菌中的生物合成和生理功能。在细菌领域很少观察到产生两组脂质的能力。因此，这种生物提供了一个很好的模型系统，用于研究藿烷类和甾醇的进化和生理意义，并期望这些研究将允许对岩石记录中甾醇和藿烷类的出现有更充分和更有力的解释。这些研究将通过微生物学和有机地球化学领域的合作努力进行。该项目将培养一名来自代表性不足的少数群体的早期职业研究科学家和一名跨学科地理生物学领域的研究生。

The majority of life's history had been dominated by microbes whose metabolic inventions have significantly altered the Earth's surface environment and, in turn, impacted the evolution of life on Earth. Yet our ability to study microbial life in the context of the Earth's distant past has remained a difficult challenge primarily because microbes do not readily leave diagnostic morphological fossils. One of the predominant strategies to overcome this challenge has been the use of "molecular fossils." This approach correlates the occurrence of preserved lipids in ancient rocks with their production in modern bacteria. Two sets of lipids that have emerged as powerful geological biomarkers are sterols, produced primarily by eukaryotes, and the sterol-like hopanoids, produced only by bacterial species. In this project, investigators will study the biosynthesis and physiological function of both of these lipids in Methylococcus capsulatus. The ability to produce both sets of lipids is rarely observed in the bacterial domain. Therefore, this organism provides an excellent model system for examining the evolutionary and physiological significance of both hopanoids and sterols with the expectation that these studies will allow for a more informed and robust interpretation of the occurrence of sterols and hopanoids in the rock record. These studies will be carried out through a collaborative effort merging the fields of microbiology and organic geochemistry. The project will train an early career research scientist from an underrepresented minority group and a graduate student in the interdisciplinary field of geobiology.