Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria.
ISME J. 2012 Apr;6(4):802-13. doi: 10.1038/ismej.2011.151. Epub 2011 Nov 17.
Knowledge about Sphagnum-associated microbial communities, their structure and their origin is important to understand and maintain climate-relevant Sphagnum-dominated bog ecosystems. We studied bacterial communities of two cosmopolitan Sphagnum species, which are well adapted to different abiotic parameters (Sphagnum magellanicum, which are strongly acidic and ombrotrophic, and Sphagnum fallax, which are weakly acidic and mesotrophic), in three Alpine bogs in Austria by a multifaceted approach. Great differences between bacterial fingerprints of both Sphagna were found independently from the site. This remarkable specificity was confirmed by a cloning and a deep sequencing approach. Besides the common Alphaproteobacteria, we found a discriminative spectrum of bacteria; although Gammaproteobacteria dominated S. magellanicum, S. fallax was mainly colonised by Verrucomicrobia and Planctomycetes. Using this information for fluorescent in situ hybridisation analyses, corresponding colonisation patterns for Alphaproteobacteria and Planctomycetes were detected. Bacterial colonies were found in high abundances inside the dead big hyalocytes, but they were always connected with the living chlorocytes. Using multivariate statistical analysis, the abiotic factors nutrient richness and pH were identified to modulate the composition of Sphagnum-specific bacterial communities. Interestingly, we found that the immense bacterial diversity was transferred via the sporophyte to the gametophyte, which can explain the high specificity of Sphagnum-associated bacteria over long distances. In contrast to higher plants, which acquire their bacteria mainly from the environment, mosses as the phylogenetically oldest land plants maintain their bacterial diversity within the whole lifecycle.
关于泥炭藓相关微生物群落的知识，包括它们的结构和起源，对于理解和维护与气候相关的以泥炭藓为主导的沼泽生态系统至关重要。我们通过多方面的方法研究了两种分布广泛的泥炭藓（Sphagnum magellanicum，强酸性和寡营养型；Sphagnum fallax，弱酸性和中营养型）的细菌群落，这两种泥炭藓适应不同的非生物参数。结果发现，两种泥炭藓的细菌指纹图谱存在很大差异，且这种显著的特异性不受地点影响。通过克隆和深度测序方法进一步证实了这一点。除了常见的α变形菌外，我们还发现了一组具有鉴别性的细菌；虽然γ变形菌在 S. magellanicum 中占主导地位，但 S. fallax 主要被疣微菌门和浮霉菌门细菌定殖。利用这些信息进行荧光原位杂交分析，检测到了相应的α变形菌和浮霉菌门的定植模式。细菌菌落大量存在于死亡的大细胞中，但它们始终与活的叶绿体相连。通过多变量统计分析，发现营养丰富度和 pH 等非生物因素调节了泥炭藓特有细菌群落的组成。有趣的是，我们发现巨大的细菌多样性通过孢子体传递到配子体，这可以解释为什么泥炭藓相关细菌具有远距离的高度特异性。与主要从环境中获取细菌的高等植物不同，作为系统发育上最古老的陆地植物，苔藓在整个生命周期中维持其细菌多样性。
