Soil macropores serve as preferential pathways for water and solute transport as well as for root growth. They are often coated with organic material and known as "hotspots" of nutrient and C turnover. Differences in the SOM composition between macropores and soil matrix as well as between macropore types (biopores, cracks, pinhole fillings) imply potential differences in the microbial community composition and enzymatic activities. The objective of this work was to detect and assess the spatial distribution of enzyme activities related to C turnover, xylanase (XYL) and phenol oxidase (POX), and the composition of microbial communities in structural components of Luvisol Bt-horizons, developed from loess and glacial till. We applied conventional enzyme assays and phospholipid fatty acids (PLFA) analysis to study materials separated from different types of macropores and soil components as well as bulk soil samples. The spatial distribution of enzyme activities on surfaces of large soil core slices (20 cm in diameter) was quantified by soil zymography. Higher XYL activities were detected in separated burrow wall materials, clay-organic coatings, and pinhole fillings from both sites, as compared to the respective soil matrix or bulk soil samples. The XYL activities correlated with bacteria-specific PLFAs. POX activities were solely found increased for earthworm burrow walls from the loess-derived Bt-horizon, but not for burrows from till samples. Zymograms revealed particularly increased XYL activities at rooted earthworm burrows, emphasising evidence for hotspots of enzyme activity and C turnover. The zymography of POX was hampered by methodological restrictions.

土壤大孔是水和溶质运输以及根系生长的优先途径。它们通常涂有有机材料，被称为养分和碳转换的“热点”。大孔与土壤基质之间以及大孔类型（生物孔，裂缝，针孔填充物）之间的SOM组成差异暗示了微生物群落组成和酶活性的潜在差异。这项工作的目的是检测和评估与黄土开发的与C周转率，木聚糖酶（XYL）和苯酚氧化酶（POX）相关的酶活性的空间分布以及Luvisol Bt地平线结构成分中的微生物群落组成和冰川。我们应用常规酶测定法和磷脂脂肪酸（PLFA）分析来研究从不同类型的大孔和土壤成分以及大块土壤样品中分离出来的物质。通过土壤酶谱定量分析大土壤芯切片（直径20厘米）表面酶活性的空间分布。与相应的土壤基质或散装土壤样品相比，在两个地点的分开的洞穴壁材料，粘土有机涂层和针孔填充物中检测到的较高的XYL活性。XYL活性与细菌特异性PLFA相关。仅发现来自黄土的Bt地平线的for洞穴壁的POX活性增加，但直到样品为止的洞穴的POX活性都没有增加。柱状图显示，根YL穴中的XYL活性特别增加，强调了酶活性和C转换热点的证据。POX的酶谱学受到方法学限制。