Investigating the roles of Fe(II)-silicate and Fe(III)-silicate complexes and nanoparticles in the survival of early cyanobacteria and photoferrotrophic bacteria

研究 Fe(II)-硅酸盐和 Fe(III)-硅酸盐复合物和纳米颗粒在早期蓝藻和光铁营养细菌存活中的作用

• 批准号: 404675831
• 负责人: Professor Dr. Andreas Kappler
• 金额: --
• 依托单位: Arbeitsgruppe Geomikrobiologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/404675831?language=en
• 关键词: Investigating; roles; Fe; II; silicate

Life evolved on Earth nearly four billion years ago, but the environmental conditions surrounding its evolution remains poorly understood. Ancient microbial fossil and isotopic records indicate the existence of thriving photosynthetic microbial ecosystems by 3.5 Ga, and perhaps as early as 3.8 Ga. However, these environments presented high levels of UV radiation and toxic iron concentrations that should have made early marine environments inhospitable to life. The answer to how ancient photosynthetic bacteria (photoferrotrophs and cyanobacteria) overcame these environmental stresses possibly lies in the composition of Archean seawater itself. High silica abundances in pre-2.5 Ga seawater may have been instrumental in the initial survival of ancient photosynthetic bacteria, as well as to the early colonization of littoral marine environments, by forming Fe(II)-silicate and Fe(III)-silicate complexes and nanoparticles in the ancient water column. These complexes and nanoparticles would have not only acted as a ‘sunscreen’ against the high levels in incident UV radiation. By complexing with iron(II), silica would have lowered the level of dissolved, bioavailable and toxic iron(II) to more manageable levels, thus enabling the survival and evolution of early bacteria under high iron conditions. In this regard, the purpose of this proposal is twofold: i) to identify the geochemical composition and physical nature of the Fe(II)-silicate and Fe(III)-silicate complexes and nanoparticles, and ii) to determine their ability at protecting free-floating (planktonic) cyanobacteria and photoferrotrophs from long-term exposure to Archean-level UV radiation. By applying information derived from the Archean rock record, to geochemical and biological models, this multidisciplinary approach will allow the elucidation of a number of important interactions between the early hydro-litho- and atmosphere, and early life.

生命在近四十亿年前就在地球上进化出来，但对其进化的环境条件仍然知之甚少。古微生物化石和同位素记录表明，3.5Ga甚至可能早在3.8Ga就存在着繁荣的光合微生物生态系统。然而，这些环境呈现出高水平的紫外线辐射和有毒的铁浓度，这应该使早期的海洋环境不适合生命。古代光合细菌（光铁营养菌和蓝细菌）如何克服这些环境压力的答案可能在于太古代海水本身的组成。在前2.5 Ga海水中的高二氧化硅丰度可能有助于古代光合细菌的最初生存，以及早期定居的沿岸的海洋环境，通过形成铁（II）-硅酸盐和铁（III）-硅酸盐复合物和纳米粒子在古代水柱。这些复合物和纳米颗粒不仅可以作为“防晒霜”来抵御高水平的入射紫外线辐射。通过与铁（II）络合，二氧化硅将溶解的、生物可利用的和有毒的铁（II）的水平降低到更易于管理的水平，从而使早期细菌能够在高铁条件下存活和进化。在这方面，该提案的目的有两个：i）确定Fe（II）-硅酸盐和Fe（III）-硅酸盐复合物和纳米颗粒的地球化学组成和物理性质，以及ii）确定它们保护自由漂浮（浮游）蓝细菌和光致铁营养生物长期暴露于太古代水平紫外线辐射的能力。通过将来自太古代岩石记录的信息应用于地球化学和生物模型，这种多学科方法将允许阐明早期水-岩石-和大气以及早期生命之间的一些重要相互作用。