Mechanisms of Calcium Carbonate Precipitation and Dissolution: Microbial Populations, Metabolic Processes and Mineral Products

Visscher摘要该项目通过对一个高盐度池塘(巴哈马Eleuthera)中微生物群落从岩化到非岩化的梯度进行地质生物学研究，研究生物活性沉积物中碳酸盐沉淀的潜在机制。现场测量和现场操作正在与各种实验室实验相结合，以分离和描述控制碳酸盐沉淀的生物过程和环境变量。PIS正在检查与碳酸盐矿物形成有关的微生物群落组成、代谢率和EPS特征。正在调查的环境参数包括水化学(例如，pH、[Ca~(2+)]、[CO32-])和光照强度。通过在分批和连续培养中进行纯细菌和混合细菌培养的实验，研究了碳酸盐沉淀中的微生物代谢(无机碳的生产/消耗)。通过关注从石化垫子到富含EPS凝胶的自然梯度的沉淀和溶解，PI希望了解控制微生物群落沉淀碳酸钙的一般规则。这些信息正被用来开发一种描述生物活性沉积物中矿物沉淀的机械理论。由于负责碳酸盐沉淀的主要微生物协会(蓝藻、硫氧化菌、硫酸盐还原菌)存在于众多环境中，因此所开发的理论将涉及整个碳酸盐工厂、微生物在形成具有重要地质意义的矿产品以及生物材料的岩化和保存中的作用。

Visscher Abstract This project is investigating the underlying mechanisms of carbonate precipitation in biologically active sediments by performing a geobiological study on a gradient from lithifying to non-lithifying microbial communities from microbial mats in a hypersaline pond (Eleuthera, Bahamas). Field measurements and in situ manipulations are being combined with a variety of laboratory experiments to isolate and characterize the biological processes and environmental variables that control carbonate precipitation. The PIs are examining microbial community composition, metabolic rates, and EPS characteristics in relation to carbonate mineral formation. Environmental parameters which are being investigated include water chemistry (e.g., pH, [Ca2+], [CO32-]) and light intensity. Microbial metabolism (production/consumption of inorganic carbon) on carbonate precipitation are being investigated by experimenting with pure and mixed bacterial cultures in both batch and continuous culture. By focusing on precipitation and dissolution along a natural gradient from lithifying mats to gelatinous EPS-rich mats, the PIs hope to understand the general rules that govern calcium carbonate precipitation by microbial communities. This information is being used to develop a mechanistic theory describing mineral precipitation in biologically active sediments. Since the main microbial guilds (cyanobacteria, sulfur oxidizers, sulfate reducers) responsible for carbonate precipitation are found in numerous environments, the theory developed will address the entire carbonate factory, the role of microbes in the formation of geologically important mineral products and the lithification and preservation of biological materials.