Abstract Aggregation of soil components is contributing to the formation of diverse habitats for microbial life. Soil aggregates of different size are known to promote niche differentiation. Moreover, aggregates differ in physical and chemical properties, therewith likely supporting biological diversity in soil. To evaluate whether different types of aggregates affect bacterial colonization, we analyzed the impact of aggregate size in dependence of soil clay content on the bacterial community composition. A further distinction was made between microaggregates that occur as free structures in the soil matrix and those that exist occluded within macroaggregates. Upon size fractionation of soil samples from a clay catena (19 – 34%), we analyzed the bacterial community composition in ten different aggregate fractions by amplicon sequencing of the 16S rRNA gene. Both the aggregate size and the clay content showed an influence on the bacterial community composition, although this influence explained only a minor amount of the total observed variation across all samples (approx. 10% each). The increasing clay content led to more distinct communities in aggregates of different size, especially the smallest microaggregate fractions (

中文翻译：

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粘土含量调节不同大小土壤团聚体中细菌群落结构的差异

摘要 土壤成分的聚集有助于微生物生命多样化栖息地的形成。已知不同大小的土壤团聚体可促进生态位分化。此外，聚集体的物理和化学特性不同，因此可能支持土壤中的生物多样性。为了评估不同类型的聚集体是否影响细菌定植，我们分析了聚集体大小与土壤粘土含量对细菌群落组成的影响。进一步区分了在土壤基质中作为自由结构出现的微团聚体和存在于大团聚体中的微团聚体。在对粘土链中的土壤样品进行尺寸分级时 (19 – 34%)，我们通过 16S rRNA 基因的扩增子测序分析了 10 个不同聚集部分中的细菌群落组成。聚集体大小和粘土含量均显示出对细菌群落组成的影响，尽管这种影响仅解释了所有样品中观察到的总变异的一小部分（每个约 10%）。粘土含量的增加导致不同大小的团聚体中更明显的群落，尤其是最小的微团聚体部分（