Intracellular metal pumping in microbial excavation by microbes

蓝细菌是最常见、分布最广、对环境影响最大的生物侵蚀剂之一，当它们在碳酸盐基质中生长时，会钻穿微观画廊。它们在化学平衡下实现这一点的机制知之甚少。我们的工作表明，钻孔可能是由膜结合的Ca2+转运ATP酶的作用驱动的，直接由光合作用产生的ATP提供动力，作用于维持远端钻孔的间隙空间中的游离Ca2+水平非常低，这种情况促进局部方解石溶解，然后Ca2+在细胞内沿着细丝中的浓度梯度向下移动以释放到外部介质中。我们打算在这里推进我们的理解，在分子，遗传和细胞水平上的钻孔机制，并测试其普遍性，通过探测其变异性的本质或细节方面的微生物剂比以前使用的模型，和矿物基质比碳酸钙。我们将实现这一目标，通过遗传和细胞的Ca2+运输系统，分子生物学技术和显微成像技术的基础上共聚焦显微镜的模式微生物的表征。 我们还将询问天然复杂的社区钻孔微生物从各种地理和矿物学设置（石灰岩，白云岩和生物碳酸盐）的遵守Ca2+运输机制。最后，新的种植努力将用于解决磷酸盐，白云石和菱镁矿的神秘挖掘，这是模型微生物缺乏的能力，但被认为是在自然界中发生的。 从描述性的理解模型转向机械性的理解模型，正如本书所尝试的，仍然是地球生物学的前沿领域之一。这项研究将试图确定微生物利用太阳能为石灰石等溶解矿物质提供动力的确切机制，而地球化学预测它们根本不应该溶解。 这些知识将提供解释几种具有广泛重要性的生物和地质现象的可能性。例如，它将涉及钙运输的生理学研究，这是在非常不同的环境中驱动人类肌肉运动的相同现象。它还可能有助于我们预测全球海洋酸化对沿海石灰石溶解的影响。它将有助于生物材料科学的潜在应用的基础知识，甚至可能提供一种手段，用于对抗工程系统中的钙化，或阻止建筑物和纪念碑的生物退化。这项研究将与教育、培训、传播和外联活动紧密结合。

Cyanobacteria are among the most common, widespread and environmentally significant agents of bio-erosion, boring microscopic galleries as they grow within carbonate substrates. The mechanisms by which they achieve this against chemical equilibrium are poorly known. Our work showed that boring is likely driven by the action of membrane-bound Ca2+ transporting ATPases, powered directly by photosynthetically derived ATP, acting to maintain the levels of free Ca2+ in the interstitial space of the distal borehole very low, a situation that promotes local calcite dissolution, with Ca2+ then travelling intra-cellularly down a concentration gradient in the filament to be released into the outside medium. We intend here to advance our understanding of the boring mechanism at the molecular, genetic and cellular level and to test its universality, by probing its variability in essence or detail with respect to microbial agents other than the models previously used, and for mineral substrates other than CaCO3. We will achieve this through genetic and cellular characterization of the Ca2+ transport systems, molecular biology techniques and micro-imaging techniques based on confocal microscopy of model microbes. We will also interrogate natural complex communities of boring microorganims from a variety of geographic and mineralogical settings (limestones, dolostones and biogenic carbonates) for their compliance with the Ca2+-transport mechanism. Finally, renewed efforts of cultivation will be used to address the mysterious excavation of phosphates, dolomite, and magnesite, a capacity that model microbes lacks, but is assumed to take place in nature. Moving from descriptive to mechanistic models of understanding, as this work will attempt, remains one of the frontiers of geobiology. The research will attempt to ascertain the exact mechanisms by which microbes can use the energy from the sun to power dissolving minerals like limestone, when geochemistry would predict they should not dissolve at all. This knowledge would offer the potential to explain several biological and geological phenomena of widespread importance. For example, it will involve the study of physiology of calcium transport, the same phenomenon that drives muscle movement in humans, in a very different setting. It may also contribute to our ability to predict the consequences of global acidification of the oceans with respect to coastal limestone dissolution. It will contribute basic knowledge with potential applications in biomaterial science, potentially even providing a means for combating calcification in engineered systems, or for deterring the bio-deterioration of buildings and monuments. The research will be intricately embedded with activities in education, training, dissemination and outreach.