Biological influence on calcification and iron oxide formation

对钙化和氧化铁形成的生物学影响

• 批准号: 5446874
• 负责人: Dr. Dirk de Beer
• 金额: --
• 依托单位: Max-Planck-Institut für Marine Mikrobiologie
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2012-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5446874?language=en
• 关键词: Biological; influence; calcification; iron; oxide

Biomineralization processes are complex reactions induced by microorganisms for energy gain and / or by the effect their activity has on the microenvironment. In the previous funding period we have focused on microbially mediated iron precipitation using the Äspö Hard Rock Laboratory as a study site. We have used high‐throughput sequencing to analyze the microbial community in the system focusing our analysis on the diversity of ironoxidizing bacteria. We found large variations between the microbial communities fed by the 3 different aquifers tested. The data showed that the dominant iron oxidizing bacteria is not Gallionella, as previously assumed. Different dominant iron oxidizer are found at different locations in the tunnel (but Gallionella is never dominant). We found that bulk measure-ments of isotope‐labeled microbial mats underestimates iron oxidation rates by up to an order of magnitude. One reason is the internal iron cycling: oxidized iron is rapidly reduced biologically supplying additional Fe2+ for iron oxidation. The contribution of abiotic precipitation of iron to the mineralization process is high, but could not be accurately quantified. We will focus the coming 2 years on the fol-lowing issues:1) How does water chemistry determine the iron‐oxidizing community composition2) Is organic matter (EPS) or biotically‐precipitated iron the main nucleation site for abiotic iron precipitation within the biofilm3) What is the actual rate of iron cycling (Fe‐reduction coupled to oxidation).The proposed study aims to elucidate which environmental conditions control biotic and abiotic iron mineralization.

生物矿化过程是由微生物为了获得能量和/或通过其活动对微环境的影响而引起的复杂反应。在之前的资助期间，我们使用 äspö Hard Rock 实验室作为研究地点，重点研究微生物介导的铁沉淀。我们使用高通量测序来分析系统中的微生物群落，重点分析铁氧化细菌的多样性。我们发现测试的 3 个不同含水层的微生物群落之间存在很大差异。数据显示，占主导地位的铁氧化细菌并不像之前假设的那样是 Gallionella。在隧道的不同位置发现了不同的主要铁氧化剂（但 Gallionella 从来不是主要的）。我们发现，同位素标记的微生物垫的批量测量低估了铁的氧化速率达一个数量级。原因之一是内部铁循环：氧化铁迅速被生物还原，为铁氧化提供额外的 Fe2+。铁的非生物沉淀对矿化过程的贡献很大，但无法准确量化。我们将在未来两年重点关注以下问题：1）水化学如何决定铁氧化群落组成2）有机物（EPS）或生物沉淀铁是生物膜内非生物铁沉淀的主要成核位点3）铁循环的实际速率是多少（铁还原与氧化相结合）。本研究旨在阐明哪些环境条件控制生物和铁氧化 非生物铁矿化。