Winogradsky Institute of Microbiology, Russian Academy of Sciences, Moscow, Russia.
PLoS One. 2013 May 21;8(5):e63994. doi: 10.1371/journal.pone.0063994. Print 2013.
Northern peatlands play a key role in the global carbon and water budget, but the bacterial diversity in these ecosystems remains poorly described. Here, we compared the bacterial community composition in the surface (0-5 cm depth) and subsurface (45-50 cm) peat layers of an acidic (pH 4.0) Sphagnum-dominated wetland, using pyrosequencing of 16S rRNA genes. The denoised sequences (37,229 reads, average length ∼430 bp) were affiliated with 27 bacterial phyla and corresponded to 1,269 operational taxonomic units (OTUs) determined at 97% sequence identity. Abundant OTUs were affiliated with the Acidobacteria (35.5±2.4% and 39.2±1.2% of all classified sequences in surface and subsurface peat, respectively), Alphaproteobacteria (15.9±1.7% and 25.8±1.4%), Actinobacteria (9.5±2.0% and 10.7±0.5%), Verrucomicrobia (8.5±1.4% and 0.6±0.2%), Planctomycetes (5.8±0.4% and 9.7±0.6%), Deltaproteobacteria (7.1±0.4% and 4.4%±0.3%), and Gammaproteobacteria (6.6±0.4% and 2.1±0.1%). The taxonomic patterns of the abundant OTUs were uniform across all the subsamples taken from each peat layer. In contrast, the taxonomic patterns of rare OTUs were different from those of the abundant OTUs and varied greatly among subsamples, in both surface and subsurface peat. In addition to the bacterial taxa listed above, rare OTUs represented the following groups: Armatimonadetes, Bacteroidetes, Chlamydia, Chloroflexi, Cyanobacteria, Elusimicrobia, Fibrobacteres, Firmicutes, Gemmatimonadetes, Spirochaetes, AD3, WS1, WS4, WS5, WYO, OD1, OP3, BRC1, TM6, TM7, WPS-2, and FCPU426. OTU richness was notably higher in the surface layer (882 OTUs) than in the anoxic subsurface peat (483 OTUs), with only 96 OTUs common to both data sets. Most members of poorly studied phyla, such as the Acidobacteria, Verrucomicrobia, Planctomycetes and the candidate division TM6, showed a clear preference for growth in either oxic or anoxic conditions. Apparently, the bacterial communities in surface and subsurface layers of northern peatlands are highly diverse and taxonomically distinct, reflecting the different abiotic conditions in microhabitats within the peat profile.
北方泥炭地在全球碳和水预算中发挥着关键作用，但这些生态系统中的细菌多样性仍描述不足。在这里，我们使用 16S rRNA 基因的焦磷酸测序，比较了酸性（pH 4.0）水藓主导湿地表层（0-5cm 深度）和亚表层（45-50cm 深度）泥炭层中的细菌群落组成。去噪序列（37229 条reads，平均长度约 430bp）与 27 个细菌门有关，与在 97%序列同一性下确定的 1269 个操作分类单元（OTUs）相对应。丰富的 OTUs 与 Acidobacteria（分别占所有分类序列的 35.5±2.4%和 39.2±1.2%）、Alphaproteobacteria（15.9±1.7%和 25.8±1.4%）、Actinobacteria（9.5±2.0%和 10.7±0.5%）、Verrucomicrobia（8.5±1.4%和 0.6±0.2%）、Planctomycetes（5.8±0.4%和 9.7±0.6%）、Deltaproteobacteria（7.1±0.4%和 4.4%±0.3%）和 Gammaproteobacteria（6.6±0.4%和 2.1±0.1%）有关。每个泥炭层的所有亚样本中，丰富的 OTUs 的分类模式都是一致的。相比之下，稀有 OTUs 的分类模式与丰富的 OTUs 不同，并且在表层和亚表层泥炭中，亚样本之间的差异很大。除了上面列出的细菌类群外，稀有 OTUs 还代表了以下群体：Armatimonadetes、Bacteroidetes、Chlamydia、Chloroflexi、Cyanobacteria、Elusimicrobia、Fibrobacteres、Firmicutes、Gemmatimonadetes、Spirochaetes、AD3、WS1、WS4、WS5、WYO、OD1、OP3、BRC1、TM6、TM7、WPS-2 和 FCPU426。表层（882 个 OTUs）的 OTU 丰富度明显高于缺氧的亚表层泥炭（483 个 OTUs），只有 96 个 OTUs 同时存在于两个数据集。研究较少的菌门的大多数成员，如 Acidobacteria、Verrucomicrobia、Planctomycetes 和候选门 TM6，在好氧或缺氧条件下的生长都表现出明显的偏好。显然，北方泥炭地的表层和亚表层中的细菌群落高度多样且在分类上有明显区别，反映了泥炭剖面微生境中的不同非生物条件。
