海底富铁硅氧化物微生物矿化的显微记录与分子机制

海底富铁硅氧化物，通常是低温弥散流热液活动的产物，广泛地分布于全球海底。尽管微生物介导的铁氧化过程被认为是这些铁硅氧化物形成的最主要原因，然而，人们对其生物矿化作用以及微生物驱动矿化的分子机制的认识仍然十分有限。我们拟选取海底热液周围不同类型的铁硅氧化物为研究对象，在构建其环境条件和地球化学体系的基础上，对富铁硅氧化物中保留的由微生物矿化形成的显微结构进行解析，判断其矿化类型、矿化过程和参与矿化的微生物类群。同时，基于铁氧化菌的分离和培养实验，鉴别微生物铁氧化这一过程的功能基因和电子传递链，构建其能量代谢途径以及耦合其它元素循环的代谢潜能，阐述微生物铁氧化的分子机制。在上述研究的基础上，综合富铁硅氧化物的微生物群落结构以及各微生物功能群的能量代谢途径预测，阐述不同类型富铁硅氧化物的生物矿化作用和矿化的微生物驱动机制及其对铁硅氧化物相关生物地球化学过程的影响。

Fe, Si-rich oxides/oxyhydroxides (called as oxides in the following text), usually as the result of low-temperature diffuse flow dispersion near hydrothermal vents, are widely distributed on the global seafloors. Although iron oxidation catalyzed by typical neutrophilic, microaerobic iron-oxidizing bacteria (FeOB) contributes primarily to the precipitation and deposition of these Fe, Si-rich oxides, little is known about their biomineralization and molecular mechanism driven by these FeOB species. In this study, several different kinds of Fe, Si-rich oxides with distinct Fe, Si contents were collected. We would like to determine their characteristics of mineralogy and geochemistry to recover their environmental conditions and geochemical regimes. The biogenic ultrastructures with specific morphologies are characterized to indicate the biomineralization occurring within these oxides and associated microbial taxa involved in these processes. We also try to isolate pure cultures with the potentiality of iron oxidation and then identify their taxonomic positions. By the analysis of comparative genomics, key function genes and electron transport chain of iron oxidation are predicted and identified from these FeOB cultures, and then energy metabolic pathways based on iron oxidation are also constructed. Meanwhile, we also analyze the metabolic pathway of iron oxidation potentially coupled with other element cycling. Based on all those works mentioned above, together with the analyses of microbial communities dwelling in these Fe, Si-rich oxides and main energy metabolism pathways from metagenomic prediction of dominant microbial lineages, we finally want to illustrate the biomineralization processes, molecular mechanism metabolically driven from microorganisms and their impact to geochemical processes within these different types of Fe, Si-rich oxides.