Grüter Dominique, Schmid Bernhard, Brandl Helmut
University of Zurich, Institute of Environmental Sciences, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
BMC Microbiol. 2006 Jul 27;6:68. doi: 10.1186/1471-2180-6-68.
Changes in aboveground plant species diversity as well as variations of environmental conditions such as exposure of ecosystems to elevated concentrations of atmospheric carbon dioxide may lead to changes in metabolic activity, composition and diversity of belowground microbial communities, both bacterial and fungal.
We examined soil samples taken from a biodiversity x CO2 grassland experiment where replicate plots harboring 5, 12, or 31 different plant species had been exposed to ambient or elevated (600 ppm) levels of carbon dioxide for 5 years. Analysis of soil bacterial communities in these plots by temporal temperature gradient gel electrophoresis (TTGE) showed that dominant soil bacterial populations varied only very little between different experimental treatments. These populations seem to be ubiquitous. Likewise, screening of samples on a high-resolution level by terminal restriction fragment length polymorphism (T-RFLP) showed that increased levels of carbon dioxide had no significant influence on both soil bacterial community composition (appearance and frequency of operational taxonomic units, OTUs) and on bacterial richness (total number of different OTUs). In contrast, differences in plant diversity levels had a significant effect on bacterial composition but no influence on bacterial richness. Regarding species level, several bacterial species were found only in specific plots and were related to elevated carbon dioxide or varying plant diversity levels. For example, analysis of T-RFLP showed that the occurrence of Salmonella typhimurium was significantly increased in plots exposed to elevated CO2 (P < 0.05).
Plant diversity levels are affecting bacterial composition (bacterial types and their frequency of occurrence). Elevated carbon dioxide does not lead to quantitative alteration (bacterial richness), whereas plant diversity is responsible for qualitative changes (bacterial diversity).
地上植物物种多样性的变化以及环境条件的改变，如生态系统暴露于高浓度大气二氧化碳中，可能导致地下微生物群落（细菌和真菌）的代谢活性、组成和多样性发生变化。
我们检测了从一个生物多样性×二氧化碳草地实验中采集的土壤样本，在该实验中，含有5种、12种或31种不同植物物种的重复样地分别暴露于环境二氧化碳水平或升高的（600 ppm）二氧化碳水平下达5年。通过时间温度梯度凝胶电泳（TTGE）对这些样地中的土壤细菌群落进行分析，结果表明，不同实验处理之间，主要土壤细菌种群的变化非常小。这些种群似乎无处不在。同样，通过末端限制性片段长度多态性（T-RFLP）在高分辨率水平上对样本进行筛选，结果显示，二氧化碳水平升高对土壤细菌群落组成（操作分类单元，OTU的出现和频率）和细菌丰富度（不同OTU的总数）均无显著影响。相比之下，植物多样性水平的差异对细菌组成有显著影响，但对细菌丰富度没有影响。在物种水平上，发现几种细菌物种仅存在于特定样地中，并且与升高的二氧化碳或不同的植物多样性水平有关。例如，T-RFLP分析表明，在暴露于升高二氧化碳水平的样地中，鼠伤寒沙门氏菌的出现显著增加（P < 0.05）。
植物多样性水平影响细菌组成（细菌类型及其出现频率）。二氧化碳升高不会导致数量上的改变（细菌丰富度），而植物多样性则导致质量上的变化（细菌多样性）。
Zotero 插件
