Biomineralization and Characterization of Calcite and Vaterite Induced by the Fungus Cladosporium sp. YPLJS']JS-14

Microbially induced calcium carbonate precipitation (MICP) by the urease-producing bacteria has wide applications in the field of geology and environmental engineering. Compared to bacteria, fungi usually possess more tolerance to high salts and heavy metals, enabling MICP induced by the urease-producing fungi to be applied to harsh environments. In this study, the carbonate minerals, induced by the urease-producing fungi isolated from marine sediments, were investigated. One of the urease-producing fungi, designated as YPLJS-14, was identified with the high efficiency of precipitating calcium carbonate. The ITS sequence of YPLJS-14 revealed that it belongs to the genus of Cladosporium. The precipitates induced by this strain were characterized by XRD, SEM, TEM, SAED, and FTIR, respectively. The results show that the mineral phase of fungal precipitates is composed of calcite and vaterite. SEM, TEM, and SAED confirm that the minerals in rhombohedral morphology are calcite and the spherical minerals are vaterite. Thermogravimetric and derivative thermogravimetric (TG/DTG) analyses show that vaterite is a thermodynamically unstable mineral phase compared to calcite and easily decomposes at lower temperatures. These findings provide a foundation for understanding the mineralization mechanism of the urease-producing fungi and the potential applications in environmental engineering.