Abstract Microbial communities dwelling in biogenic structures shaped by soil macroorganisms (e.g. rhizosphere of plants, drilosphere of earthworms) are often compared to communities in the bulk soil taken as a control. Two strategies are currently applied, by sampling either bulk soil surrounding the biogenic structures inside the same experimental unit (“surrounding bulk”) or soil from a distinct control unit without macroorganism (“pristine bulk”). While surrounding bulk is commonly used, no studies explicitly compared these two bulk types. Moreover, the potential effect of plants and earthworms on microbial communities in the surrounding bulk could depend on soil properties. In controlled conditions, we exposed three soils with contrasting properties to either a plant, earthworms, both, or without macroorganisms (pristine bulk). Root-adhering soil, casts and their surrounding bulk were retrieved by meticulous sampling. We found that molecular abundances of bacteria, fungi and archaea were modified in surrounding compared to pristine bulk. In a non-trivial manner, bacterial community structure from surrounding bulk was significantly altered by plants in all soils, while the influence of earthworms was soil-dependent, in a way related to C and N contents rather than texture. When comparing macroorganism influenced versus non-influenced soils, the pristine bulk should thus be preferred, whereas the surrounding bulk is appropriate to characterize the sphere of influence of biogenic structures.

中文翻译：

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为根际和旱际微生物研究对对照大块土壤取样

摘要 居住在由土壤宏观生物（例如植物的根际、蚯蚓的旱生圈）形成的生物结构中的微生物群落经常与作为对照的大块土壤中的群落进行比较。目前采用两种策略，通过对同一实验单元内生物结构周围的大块土壤（“周围大块”）或来自没有宏观生物的不同控制单元（“原始大块”）的土壤进行取样。虽然通常使用周围散装，但没有研究明确比较这两种散装类型。此外，植物和蚯蚓对周围大块微生物群落的潜在影响可能取决于土壤特性。在受控条件下，我们将三种具有对比性质的土壤暴露于植物、蚯蚓，两者或没有大型生物（原始块体）。通过细致的取样回收了附着根的土壤、铸件及其周围的大块。我们发现，与原始体积相比，周围环境中细菌、真菌和古细菌的分子丰度发生了变化。以一种非平凡的方式，所有土壤中的植物都显着改变了周围大部分的细菌群落结构，而蚯蚓的影响是土壤依赖性的，与 C 和 N 含量有关，而不是与质地有关。在比较受微生物影响的土壤与未受影响的土壤时，原始体积应该是首选，而周围的体积适合表征生物结构的影响范围。与原始体积相比，周围的真菌和古细菌发生了变化。以一种非平凡的方式，所有土壤中的植物都显着改变了周围大部分的细菌群落结构，而蚯蚓的影响是土壤依赖性的，与 C 和 N 含量有关，而不是与质地有关。在比较受微生物影响的土壤与未受影响的土壤时，原始体积应该是首选，而周围的体积适合表征生物结构的影响范围。与原始体积相比，周围的真菌和古细菌发生了变化。以一种非平凡的方式，所有土壤中的植物都显着改变了周围大部分的细菌群落结构，而蚯蚓的影响是土壤依赖性的，与 C 和 N 含量有关，而不是与质地有关。在比较受微生物影响的土壤与未受影响的土壤时，原始体积应该是首选，而周围的体积适合表征生物结构的影响范围。