State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China; Graduate University of Chinese Academy of Sciences, Beijing 100039, China.
Bioresour Technol. 2011 Jan;102(2):1562-6. doi: 10.1016/j.biortech.2010.08.080. Epub 2010 Aug 26.
Formation of CaCO3 induced by fungal physiological activities is a potential way to sequestrate atmospheric CO2 in ecosystem. Alternaria sp. is a saprophytic fungus isolated from a forest soil. We examined the precipitation of CaCO3 induced by the fungus in response to different levels of Ca(NO3)2 or CaCl2 in agar media, and the biogenesis of CaCO3 was verified by low δ13C value. The formed CaCO3 was identified as calcite by X-ray diffraction analysis. Square, rectangular and rhombic CaCO3 crystals and amorphous calcium carbonate were observed around mycelia at higher levels of Ca(NO3)2. Acidification occurred in media at low concentrations (0 and 0.0002 M) of Ca(NO3)2, and no CaCO3 formed in these media. The quantities of CaCO3 formed in media increased with increasing concentrations of Ca(NO3)2 and were significantly correlated to fungal biomass, pH value and nitrite concentrations. No CaCO3 was formed in media with CaCl2 at all levels. These results collectively indicated that the formation of CaCO3 can be induced by the fungal assimilation of nitrate. The study also revealed that biogenic crystal of CaCO3 tended to grow on a silicon nucleus and the amorphous calcium carbonate (ACC) was the transient stage of CaCO3 crystal.
真菌生理活动诱导碳酸钙形成是生态系统中固定大气 CO2 的一种潜在途径。链格孢（Alternaria sp.）是从森林土壤中分离出的一种腐生真菌。我们研究了在琼脂培养基中不同 Ca(NO3)2 或 CaCl2 水平下真菌诱导碳酸钙沉淀的情况，并通过低 δ13C 值验证了碳酸钙的生物成因。通过 X 射线衍射分析，确定形成的碳酸钙为方解石。在较高 Ca(NO3)2 水平下，在菌丝周围观察到了方解石、矩形和菱形碳酸钙晶体和无定形碳酸钙。在 Ca(NO3)2 浓度较低（0 和 0.0002 M）的培养基中发生酸化，且这些培养基中未形成碳酸钙。随着 Ca(NO3)2 浓度的增加，培养基中形成的碳酸钙量增加，并与真菌生物量、pH 值和亚硝酸盐浓度显著相关。在所有 CaCl2 水平的培养基中均未形成碳酸钙。这些结果表明，碳酸钙的形成可以被真菌同化硝酸盐所诱导。该研究还表明，生物成因碳酸钙晶体倾向于在硅核上生长，而无定形碳酸钙（ACC）是碳酸钙晶体的过渡阶段。
