Biodiversität und DNA-Taxonomie von Algen und Cyanobakterien in kalzifizierenden Biofilmen

验证和进一步阐明蓝藻和微藻在叠层石形成中的分类群特异性活性是本项目的主要目标。在前一个项目阶段，发现了两个样本凝灰岩小溪的蓝藻和硅藻，现在需要探索它们的现场丰度和与CaCO3沉淀物和无CaCO3地区相关的分布模式。这将通过rRNA靶向荧光原位杂交进行可视化。还将测试主要参与者蓝藻和藻类的钙化潜力，其中还包括建立新的培养物。为了进一步研究蓝藻对叠层石形成的控制，需要调查来自与凝灰岩小溪明显不同的水域的蓝藻，因此，将选择圣诞岛(Kiritimati)高盐度环境中的层状微生物垫子。石灰华小溪生物膜分类组成的季节性变化可能是形成石灰华的一个可能的额外驱动力，这将用快速分子方法进行评估。前一个项目阶段的结果表明，硅藻以外的真核藻类与钙化有关的多样性可能还被低估，因此将在这里使用与培养无关的方法进一步评估。

To verify and further elucidate taxon-specific activities of cyanobacteria and microalgae in stromatolite formation is the main goal of this project. In the previous project phase key player cyanobacteria and diatoms from two exemplar tufa creeks were revealed and it is now needed to explore their in situ abundances and distribution patterns in relation to CaCO3 precipitates and CaCO3-free areas. This will be visualized by rRNA-targeted Fluorescence In Situ Hybridization. The calcification potential of the key player cyanobacteria and algae will be tested as well which includes the establishment of new cultures as well. To further investigate the cyanobacterial control of stromatolite formation, cyanobacteria from a water setting significantly different from the tufa creeks need to be investigated and, therefore, the stratified microbial mats in the hypersaline environment at Christmas island (Kiritimati) will be selected. Seasonal changes in the taxonomic composition of the tufa creek biofilms may act as a possible additional driving force of tufa formation which will be assessed using rapid molecular methods. Results from the previous project phase indicate that the diversity of eukaryotic algae other than diatoms in relation to calcification may yet have been underestimated and thus it will be further evaluated here using culture-independent methods.