Thünen-Institut für Biodiversität, Braunschweig, Germany.
FEMS Microbiol Ecol. 2013 Oct;86(1):71-84. doi: 10.1111/1574-6941.12092. Epub 2013 Mar 6.
The objective of this study was to characterize the microbial communities attached to clay (< 2 μm), fine silt (2-20 μm), coarse silt (20-63 μm) and sand-sized fractions [> 63 μm; including particulate organic matter (POM)] of an arable soil and analyse their response to more than 100 years of two different fertilization regimes. Mild ultrasonic dispersal, wet-sieving and centrifugation allowed the separation of soil particles with the majority of bacterial cells and DNA still attached. Fertilizations increased soil organic carbon (SOC), total DNA and the abundance of bacterial, archaeal and fungal rRNA genes more strongly in the larger-sized fractions than in fine silt, and no effect was seen with clay, the latter representing above 70% of the total microbial populations. A highly positive correlation was found between microbial rRNA genes and the surface area provided by the particles, while the correlation with SOC was lower, indicating a particle-size-specific heterogeneous effect of SOC. The prokaryotic diversity responded more strongly to fertilization in the larger particles but not with clay. Overall, these results demonstrate that microbial responsiveness to long-term fertilization declined with smaller particle sizes and that especially clay fractions exhibit a high buffering capacity protecting microbial cells against changes even after 100 years under different agricultural management.
本研究的目的是描述附着在耕地土壤粘粒（<2μm）、细粉粒（2-20μm）、粗粉粒（20-63μm）和砂粒级（>63μm；包括颗粒有机物质（POM））上的微生物群落的特征，并分析它们对超过 100 年的两种不同施肥制度的响应。温和的超声分散、湿筛和离心允许分离出大部分仍附着有细菌细胞和 DNA 的土壤颗粒。施肥对较大颗粒（>63μm）中的土壤有机碳（SOC）、总 DNA 以及细菌、古菌和真菌 rRNA 基因的丰度的增加作用强于细粉粒（2-20μm），而对粘粒（<2μm）没有影响，后者代表了超过 70%的总微生物群体。发现微生物 rRNA 基因与颗粒提供的表面积之间存在高度正相关，而与 SOC 的相关性较低，表明 SOC 存在颗粒大小特异性的不均匀效应。在较大颗粒中，原核生物多样性对施肥的响应更强，但粘粒没有。总体而言，这些结果表明，微生物对长期施肥的响应随着颗粒尺寸的减小而降低，特别是粘粒表现出很高的缓冲能力，即使在不同农业管理下经过 100 年后，仍能保护微生物细胞免受变化的影响。
