University of Northern British Columbia, Prince George, British Columbia, Canada.
Appl Environ Microbiol. 2009 Nov;75(22):7079-85. doi: 10.1128/AEM.00325-09. Epub 2009 Sep 25.
Piloderma fallax is an ectomycorrhizal fungus commonly associated with several conifer and hardwood species. We examined the formation of calcium oxalate crystals by P. fallax in response to calcium (0.0, 0.1, 0.5, 1, and 5 mM) and phosphorus (0.1 and 6 mM) additions in modified Melin-Norkrans agar medium. Both calcium and phosphorus supplementation significantly affected the amount of calcium oxalate formed. More calcium oxalate was formed at high P levels. Concentrations of soluble oxalate in the fungus and medium were higher at low P levels. There was a strong positive linear relationship between Ca level and calcium oxalate but only under conditions of phosphorus limitation. Calcium oxalate crystals were identified as the monohydrate form (calcium oxalate monohydrate [COM] whewellite) by X-ray diffraction analysis. Prismatic, styloid, and raphide forms of the crystals, characteristic COM, were observed on the surface of fungal hyphae by scanning electron microscopy. P. fallax may be capable of dissolving hyphal calcium oxalate under conditions of limited Ca. The biomineralization of calcium oxalate by fungi may be an important step in the translocation and cycling of Ca and P in soil.
易生根皮孔菌是一种外生菌根真菌，通常与几种针叶树和阔叶树种有关。我们研究了易生根皮孔菌在改良的 Melin-Norkrans 琼脂培养基中对钙（0.0、0.1、0.5、1 和 5mM）和磷（0.1 和 6mM）添加的反应中草酸钙晶体的形成。钙和磷的补充都显著影响草酸钙的形成量。在高磷水平下形成更多的草酸钙。在低磷水平下，真菌和培养基中可溶草酸盐的浓度更高。在磷限制条件下，Ca 水平与草酸钙之间存在很强的正线性关系。通过 X 射线衍射分析鉴定草酸钙晶体为一水合物形式（草酸钙一水合物[COM] 尿酸）。扫描电子显微镜观察到真菌菌丝表面有棱柱形、棒状和针状晶体，这是 COM 的特征。在钙有限的情况下，易生根皮孔菌可能能够溶解菌丝体中的草酸钙。真菌对草酸钙的生物矿化可能是土壤中钙和磷迁移和循环的重要步骤。
