Intracellular metal pumping in microbial excavation by microbes

蓝藻是最常见的，广泛的和环境显著的生物侵蚀剂，镗孔微观画廊，因为他们在碳酸盐基质内生长。它们在化学平衡中实现这一目标的机制尚不清楚。我们的工作表明，钻孔可能是由膜结合的Ca2+运输ATP酶的作用驱动的，由光合作用衍生的ATP直接驱动，作用于维持远端钻孔间隙中游离Ca2+的水平非常低，这种情况促进局部方解石溶解，然后Ca2+在细胞内沿丝的浓度梯度向下移动，释放到外部介质中。我们打算在这里推进我们在分子、遗传和细胞水平上对无聊机制的理解，并通过探索其本质上或细节上的可变性来测试其普遍性，这些可变性与之前使用的模型之外的微生物剂和CaCO3以外的矿物基质有关。我们将通过Ca2+运输系统的遗传和细胞特征，分子生物学技术和基于模型微生物共聚焦显微镜的微成像技术来实现这一目标。我们还将询问来自各种地理和矿物学环境（石灰石，白云岩和生物成因碳酸盐岩）的自然复杂微生物群落，以了解它们对Ca2+运输机制的遵从性。最后，新的栽培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，但被认为在自然界中发生。从描述性到机械性的理解模型，正如这项工作将尝试的那样，仍然是地理生物学的前沿之一。这项研究将试图确定微生物利用太阳能量来溶解矿物质（如石灰石）的确切机制，而地球化学预测这些矿物质根本不应该溶解。这种知识将为解释一些具有广泛重要性的生物和地质现象提供可能。例如，它将涉及钙运输的生理学研究，这是在一个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岩溶解的影响。它将为生物材料科学的潜在应用提供基础知识，甚至可能为工程系统中的钙化或阻止建筑物和纪念碑的生物退化提供一种手段。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.