Biotite weathering and nutrient uptake by ectomycorrhizal fungus, Suillus tomentosus, in liquid-culture experiments
Biotite weathering and nutrient uptake by ectomycorrhizal fungus, Suillus tomentosus, in liquid-culture experiments
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DOI：
10.1016/j.gca.2008.04.003
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发表时间：
2008-06-01
影响因子：
5
通讯作者：
Bormann, Bernard T.
中科院分区：
文献类型：
--
作者：
Balogh-Brunstad, Zsuzsanna;Keller, C. Kent;Bormann, Bernard T.
外生菌根真菌（EMF）改变了维管植物的养分获取能力，并可能在养分有限条件下的土壤矿物风化和风化产物分配中发挥重要作用。在这项研究中，我们分离的风化功能的绒毛乳牛肝菌在液体培养与黑云母在室温下孵育。我们假设，真菌将加速风化菌丝附着黑云母表面和传输的营养阳离子通过直接交换到真菌生物量。我们结合了质量平衡的方法，扫描电子显微镜（SEM）和原子力显微镜（AFM），以估计风化速率和黑云母表面上的溶解特性研究。与不含真菌但添加无机酸的摇动对照相比，在含有真菌的摇动液体培养物中黑云母薄片的风化快约2-3个数量级。在未经摇动的培养物中添加真菌会导致比不含真菌的无机pH对照更高的溶解速率，但并不比不含真菌的有机pH对照明显更快。在振荡培养中，黑云母中的K+、Mg 2+和Fe 2+优先分配到真菌生物质中，而在非振荡培养中，生物质中的K+和Mg 2+损失殆尽，Fe 2+的生物积累量也少得多。真菌菌丝附着在黑云母表面，但扫描电子显微镜观察不到明显的表面变化。当培养物被摇动时，基底平面的AFM图像似乎更粗糙，并且具有丰富的溶解通道，但是这种通道的发展在非摇动条件下是次要的。即使在振荡条件下，通道也仅占2.7 × 10 ~（-10）mol黑云母m ~（-2）s ~（-1）总溶解速率的1/100。结果表明，真菌风化主要发生的附着和直接转移的营养物质通过菌丝，但由于酸化的散装液体由有机酸，真菌呼吸（CO2），和络合的阳离子加速溶解的黑云母。结果进一步表明，碳水化合物源（丰富的这里）和主机与营养素交换（缺少这里）可能需要EMF发挥重要的风化作用在土壤中。土壤中营养丰富的矿物质的不饱和条件和物理分散也可能有利于菌丝的生长和附着，并促进附着介导的风化，这在土壤矿物表面的其他地方已经观察到。(C)2008爱思唯尔有限公司保留所有权利。
Ectomycorrhiza-forming fungi (EMF) alter the nutrient-acquisition capabilities of vascular plants, and may play an important role in mineral weathering and the partitioning of products of weathering in soils under nutrient-limited conditions. In this study, we isolated the weathering function of Suillus tomentosus in liquid-cultures with biotite micas incubated at room temperature. We hypothesized that the fungus would accelerate weathering by hyphal attachment to biotite surfaces and transmission of nutrient cations via direct exchange into the fungal biomass. We combined a mass-balance approach with scanning electron microscopy (SEM) and atomic force microscopy (AFM) to estimate weathering rates and study dissolution features on biotite surfaces. Weathering of biotite flakes was about 2-3 orders of magnitude faster in shaken liquid-cultures with fungus compared to shaken controls without fungus, but with added inorganic acids. Adding fungus in nonshaken cultures caused a higher dissolution rate than in inorganic pH controls without fungus, but it was not significantly faster than organic pH controls without fungus. The K+, Mg2+ and Fe2+ from biotite were preferentially partitioned into fungal biomass in the shaken cultures, while in the nonshaken cultures, K+ and Mg2+ was lost from biomass and Fe2+ bioaccurnulated much less. Fungal hyphae attached to biotite surfaces, but no significant surface changes were detected by SEM. When cultures were shaken, the AFM images of basal planes appeared to be rougher and had abundant dissolution channels, but such channel development was minor in nonshaken conditions. Even under shaken conditions the channels only accounted for only 1/100 of the total dissolution rate of 2.7 x 10(-10) mol of biotite m(-2) s(-1). The results suggest that fungal weathering predominantly occurred not by attachment and direct transfer of nutrients via hyphae, but because of the acidification of the bulk liquid by organic acids, fungal respiration (CO2), and complexation of cations which accelerated dissolution of biotite. Results further suggest that both carbohydrate source (abundant here) and a host with which nutrients are exchanged (missing here) may be required for EMF to exert an important weathering effect in soils. Unsaturated conditions and physical dispersal of nutrient-rich minerals in soils may also confer a benefit for hyphal growth and attachment, and promote the attachment-mediated weathering which has been observed elsewhere on soil mineral surfaces. (C) 2008 Elsevier Ltd. All rights reserved.