Microbial cell-envelope fragments and the formation of soil organic matter: a case study from a glacier forefield
Microbial cell-envelope fragments and the formation of soil organic matter: a case study from a glacier forefield
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DOI：
10.1007/s10533-012-9791-3
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发表时间：
2013-05
期刊：
影响因子：
4
通讯作者：
C. Schurig;R. Smittenberg;J. Berger;F. Kraft;S. Woche;Marc‐O. Goebel;H. Heipieper;A. Miltner;M. Kaestner
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文献类型：
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作者：
C. Schurig;R. Smittenberg;J. Berger;F. Kraft;S. Woche;Marc‐O. Goebel;H. Heipieper;A. Miltner;M. Kaestner
土壤发生过程中土壤有机质（SOM）的成因一直是土壤学中有争议的问题。最近，有人假设，微生物的细胞被膜碎片有助于显着SOM的形成。我们测试了这一过程的相关性在成土作用评价的SOM沿着的冰川前田（达玛冰川）的年代序列的发展。沿着前田收集的土壤年龄增加的样品进行了分析的C和N含量，磷脂和总脂肪酸（PLFA和tFA），水接触角，微疏水性和微生物细胞包膜残留物的表面覆盖。通过分析代表性的等比例扫描电子显微照片（SEM），对表面覆盖度进行可视化和定量。增加SOM含量的同时，增加覆盖面和整体丰度的微生物细胞包膜片段的基础上进行评估的扫描电子显微镜，这也反映在tFA和PLFA的量，C/N比的趋势，和增加的疏水性和水接触角的土壤样品。利用扫描电子显微镜和图像分析方法，我们可以对冰川前田新发展的生态系统中SOM的发育提供基于过程的描述。扫描电子显微镜下可见的大多数小尺寸SOM似乎由细胞死亡后保持稳定的细菌细胞包膜片段组成，因此它们的形状不会随土壤年龄而改变。我们的研究结果表明，微生物处理的SOM的重要性，并强调微生物necromass的存在，即使在土壤发育的后期阶段的细颗粒SOM的一个重要组成部分。
Genesis of soil organic matter (SOM) during pedogenesis is still a matter of controversy in soil science. Recently, it was hypothesized that microbial cell-envelope fragments contribute significantly to SOM formation. We tested the relevance of this process during pedogenesis by evaluating the development of SOM along a chronosequence of a glacier forefield (Damma glacier). Samples of increasing soil age collected along the forefield were analyzed for C and N contents, phospholipid and total fatty acids (PLFA and tFA), water contact angle, micro-hydrophobicity and surface coverage by microbial cell-envelope residues. The surface coverage was visualized and quantified by analysis of representative, equally-scaled scanning electron micrographs (SEM). Increasing SOM contents were accompanied by increasing coverage and overall abundance of microbial cell-envelope fragments as evaluated on the basis of scanning electron microscopy; this is also reflected in the amounts of tFA and PLFA, the trend of C/N ratios, and the increasing hydrophobicity and water contact angles of the soil samples. Using SEM and the image analysis approach, we can provide a process-based description of the development of SOM in the newly developing ecosystem of the glacier forefield. The majority of small-sized SOM visible with scanning electron microscopy appears to consist of bacterial cell envelope fragments that remain stable after cell death, such that their shape does not change with soil age. Our results show the importance of microbial processing of SOM, and highlight the existence of microbial necromass as a significant part of the fine-particulate SOM even in later stages of soil development.