Cappa Margherita, Perego Camilla, Terzis Dimitrios, Principi Pamela
Environmental Biotechnology, Institute of Microbiology, Department of Environment, Construction and Design, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Manno, Switzerland.
Swiss Federal Institute of Technology, Lausanne (EPFL), Faculty of Environment, Architecture and Civil Engineering (ENAC), Lausanne, Switzerland.
Sci Rep. 2025 Jul 1;15(1):21861. doi: 10.1038/s41598-025-07323-9.
Microbially induced calcite precipitation (MICP) has long been the focus of material scientists, environmental microbiologists and civil engineers because of its potential to yield biosynthesized binders that can serve as alternatives to cement or resins. Several microbial strains play crucial roles in this process and catalyse pathways for the formation of minerals, which are believed to substantially reduce the environmental impact of building materials and activities. Among the studied strains, Bacillus megaterium is not as common as Sporosarcina species. The latter microorganisms are well known to drive the fastest ureolytic-driven MICP process, i.e., precipitation of CaCO after urea breakdown into carbonate and CaCl addition to the system. This paper sheds light on the activities of B. megaterium, which possesses dual enzymatic capabilities for MICP and is equipped with both the enzymes urease and carbonic anhydrase. We postulate that, depending on the growth conditions, B. megaterium can activate either of these genes to ultimately induce CaCO precipitation. Herein, experiments are carried out in open and closed systems. C-labelled urea is employed to identify the carbon source in the precipitated CaCO. The results from Fourier transform infrared spectroscopy (FTIR) revealed the precipitation of calcite. In the presence of urea and CO at atmospheric levels, B. megaterium activates the ureolytic pathway to perform urea hydrolysis. However, at increased CO levels, more precisely, at levels greater than 470 times the atmospheric level, carbonic anhydrase is activated, catalysing the hydration of the molecule to produce HCO. When C-labelled urea was utilized, only 6% of the precipitated CaCO mineral was linked to ureolysis, and it was found that the remaining 94% was formed due to the mineralization of CO. Overall, in this work, we aim to introduce the process conditions and protocols that favour the sequestration of atmospheric CO as CaCO via the metabolic activities of B. megaterium.
微生物诱导碳酸钙沉淀（MICP）长期以来一直是材料科学家、环境微生物学家和土木工程师关注的焦点，因为它有潜力产生生物合成粘结剂，可作为水泥或树脂的替代品。几种微生物菌株在这一过程中发挥着关键作用，并催化矿物质形成途径，据信这可大幅降低建筑材料和活动对环境的影响。在所研究的菌株中，巨大芽孢杆菌不如芽孢八叠球菌属常见。后一种微生物以驱动最快的尿素分解驱动的MICP过程而闻名，即在尿素分解成碳酸盐并向系统中添加氯化钙后碳酸钙沉淀。本文揭示了巨大芽孢杆菌的活性，它具有用于MICP的双重酶促能力，并配备了脲酶和碳酸酐酶两种酶。我们推测，根据生长条件，巨大芽孢杆菌可以激活这些基因中的任何一个，最终诱导碳酸钙沉淀。在此，实验在开放和封闭系统中进行。使用¹³C标记的尿素来确定沉淀碳酸钙中的碳源。傅里叶变换红外光谱（FTIR）结果显示了方解石的沉淀。在大气水平的尿素和二氧化碳存在下，巨大芽孢杆菌激活尿素分解途径进行尿素水解。然而，在二氧化碳水平升高时，更确切地说，在高于大气水平470倍的水平下，碳酸酐酶被激活，催化该分子水合产生碳酸氢根。当使用¹³C标记的尿素时，只有6%的沉淀碳酸钙矿物与尿素分解有关，并且发现其余94%是由于二氧化碳矿化形成的。总体而言，在这项工作中，我们旨在介绍有利于通过巨大芽孢杆菌的代谢活动将大气中的二氧化碳封存为碳酸钙的工艺条件和方案。
