Geomicrobiology Group, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK.
Concrete Technology Group, Department of Civil Engineering, University of Dundee, Dundee, DD1 4HN, Scotland, UK.
Appl Microbiol Biotechnol. 2019 Sep;103(17):7217-7230. doi: 10.1007/s00253-019-09961-2. Epub 2019 Jul 9.
The ureolytic activity of Neurospora crassa results in an alkaline carbonate-rich culture medium which can precipitate soluble metals as insoluble carbonates. Such carbonates are smaller, often of nanoscale dimensions, than metal carbonates synthesized abiotically which infers that fungal excreted products can markedly affect particle size. In this work, it was found that amino acid excretion was a significant factor in affecting the particle size of copper carbonate. Eleven different amino acids were found to be secreted by Neurospora crassa, and L-glutamic acid, L-aspartic acid and L-cysteine were chosen to examine the impact of amino acids on the morphology and chemical composition of copper carbonate minerals. X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) were used to characterize the obtained copper carbonate samples. Copper carbonate nanoparticles with a diameter of 100-200 nm were produced with L-glutamic acid, and the presence of L-glutamic acid was found to stabilize these particles in the early phase of crystal growth and prevent them from aggregation. FTIR and TG analysis revealed that the amino acid moieties were intimately associated with the copper mineral particles. Component analysis of the final products of TG analysis of the copper minerals synthesized under various conditions showed the ultimate formation of Cu, CuO and CuS, suggesting a novel synthesis method for producing these useful Cu-containing materials.
粗糙脉孢菌的脲酶活性会导致培养基呈碱性且富含碳酸盐，从而使可溶性金属沉淀为不溶性碳酸盐。这些碳酸盐的粒径比非生物合成的碳酸盐小，通常为纳米级，这表明真菌分泌的产物可以显著影响颗粒大小。在这项工作中，发现氨基酸的分泌是影响碳酸铜颗粒大小的一个重要因素。发现粗糙脉孢菌分泌了 11 种不同的氨基酸，选择 L-谷氨酸、L-天冬氨酸和 L-半胱氨酸来研究氨基酸对碳酸铜矿物形貌和化学组成的影响。采用 X 射线粉末衍射（XRPD）、扫描电子显微镜（SEM）、傅里叶变换红外（FTIR）光谱、热重分析（TGA）和 X 射线光电子能谱（XPS）对所得碳酸铜样品进行了表征。L-谷氨酸可生成直径为 100-200nm 的碳酸铜纳米颗粒，并且发现 L-谷氨酸在晶体生长的早期阶段稳定这些颗粒并防止它们聚集。FTIR 和 TG 分析表明，氨基酸基团与铜矿物颗粒密切相关。在不同条件下合成的铜矿物的 TG 分析的最终产物的成分分析表明，最终形成了 Cu、CuO 和 CuS，这为这些有用的含铜材料的新型合成方法提供了依据。
