DeepEarthshape: Geomicrobiology"Iron-metabolizing bacteria as a driving force in weathering of silicate minerals"

过去几十年的研究表明，微生物在地质环境中作为风化剂发挥着关键作用，部分原因是它们能够催化矿物中所含金属的氧化还原转化。以往对这一过程的研究主要集中在微生物氧化游离Fe2+或还原铁氧化物，或Fe(III)还原细菌对粘土矿物的影响上。虽然这些都是风化过程的重要方面，但这些矿物本身就是风化产物。铁代谢细菌也可以广泛地促进土壤母质的早期形成，但这种可能性的程度尚不确定。此外，这些细菌相对于土壤发育阶段的分布、丰度和特性几乎完全未知，特别是在微生物铁循环的氧化方面。对生态认识的缺乏在很大程度上是由于这样一个事实，即尽管铁代谢细菌具有重要的生物地球化学影响，但它们在整个微生物群落中的丰度往往很低。要确定铁代谢过程对土壤发育的潜在重大影响，需要有针对性地结合敏感的分子方法和基于培养的方法来处理这些特定微生物。然而，许多这样的微生物的培养只能用专门的技术来完成。我们假设，在土壤发育过程中，铁代谢细菌群落将与地质环境共同进化，它们的活动反过来将提高土壤发育的速度。我们还认为，铁循环社区成员的身份和生理将受到气候的强烈影响，因此他们对土壤形成的贡献将随着气候的不同而不同。因此，我们建议利用智利沿海伞形藻显著的气候梯度来确定在四种不同的气候制度下，铁代谢细菌的丰度、分布和身份与整个风化剖面(从表层到基岩)铁源性质之间的相关性。然后，我们将利用微观世界实验来量化这些细菌对铁硅酸盐矿物风化速率和矿物转化的影响。最终，我们的目标是展示这些特殊的细菌是如何塑造地球表面的。

Decades of previous research have elucidated that microorganisms play a crucial role as weathering agents in geological environments, in part due to their ability to catalyse redox transformations of metals contained within minerals. Much of the previous work on this process has focused on the microbial oxidation of free Fe2+ or reduction of iron oxides, or the effect of Fe(III)-reducing bacteria on clay minerals. Whilst these are important aspects of the weathering process, these minerals are themselves weathering products. Fe-metabolizing bacteria could also contribute extensively to early formation of soil parent material, but the extent to which this is possible is undetermined. Furthermore, the distribution, abundance and identity of these bacteria relative to the stage of soil development (thus nature of the available iron source) is almost completely unknown, especially on the oxidative side of the microbial iron cycle. Much of this lack of ecological understanding results from the fact that Fe-metabolizing bacteria often have low abundance in the overall microbial community despite their important biogeochemical impact. Determination of the potentially large impact of Fe-metabolizing processes on soil development requires a targeted combination of sensitive molecular- and cultivation-based approaches towards these specific microorganisms. Cultivation of many of these organisms, however, can only be done with specialist techniques.We hypothesize that the Fe-metabolizing bacterial community will co-evolve with the geological environment during soil development, and that their activity, in turn, will enhance the rate of soil development. We also suggest that the identity and physiology of the Fe-cycling community members will be strongly influenced by climate, thus their contribution to soil formation will differ as a function of this. Therefore, we propose to use the dramatic climate gradient of the Chilean coastal cordillera to determine the correlation between the abundance, distribution and identity of Fe-metabolizing bacteria with the nature of the iron source throughout the weathering profile (from surface to bedrock) under four different climate regimes. We will then utilize microcosm experiments to quantify the effect of these bacteria on weathering rates of Fe-silicate minerals and mineral transformation. Ultimately, we aim to demonstrate how these specialized bacteria act to shape the Earth’s surface.