Beier Sara, Witzel Karl-Paul, Marxsen Jürgen
Limnologische Fluss-Station des Max-Planck-Instituts für Limnologie, Damenweg 1, 36110 Schlitz, Germany.
Appl Environ Microbiol. 2008 Jan;74(1):188-99. doi: 10.1128/AEM.00327-07. Epub 2007 Nov 16.
The bacterial community composition in small streams and a river in central Germany was examined by temperature gradient gel electrophoresis (TGGE) with PCR products of 16S rRNA gene fragments and sequence analysis. Complex TGGE band patterns suggested high levels of diversity of bacterial species in all habitats of these environments. Cluster analyses demonstrated distinct differences among the communities in stream and spring water, sandy sediments, biofilms on stones, degrading leaves, and soil. The differences between stream water and sediment were more significant than those between sites within the same habitat along the stretch from the stream source to the mouth. TGGE data from an entire stream course suggest that, in the upper reach of the stream, a special suspended bacterial community is already established and changes only slightly downstream. The bacterial communities in water and sediment in an acidic headwater with a pH below 5 were highly similar to each other but deviated distinctly from the communities at the other sites. As ascertained by nucleotide sequence analysis, stream water communities were dominated by Betaproteobacteria (one-third of the total bacteria), whereas sediment communities were composed mainly of Betaproteobacteria and members of the Fibrobacteres/Acidobacteria group (each accounting for about 25% of bacteria). Sequences obtained from bacteria from water samples indicated the presence of typical cosmopolitan freshwater organisms. TGGE bands shared between stream and soil samples, as well as sequences found in bacteria from stream samples that were related to those of soil bacteria, demonstrated the occurrence of some species in both stream and soil habitats. Changes in bacterial community composition were correlated with geographic distance along a stream, but in comparisons of different streams and rivers, community composition was correlated only with environmental conditions.
采用温度梯度凝胶电泳（TGGE）技术，结合16S rRNA基因片段的PCR产物及序列分析，对德国中部小溪和河流中的细菌群落组成进行了研究。复杂的TGGE条带模式表明，这些环境中所有栖息地的细菌物种多样性水平较高。聚类分析表明，溪水、泉水、沙质沉积物、石头上的生物膜、腐烂树叶和土壤中的群落存在明显差异。溪水和沉积物之间的差异比沿溪流从源头到河口同一栖息地内不同地点之间的差异更为显著。来自整条溪流的TGGE数据表明，在溪流上游，一个特殊的悬浮细菌群落已经形成，并且在下游仅略有变化。pH值低于5的酸性源头水中的水和沉积物中的细菌群落彼此高度相似，但与其他地点的群落明显不同。通过核苷酸序列分析确定，溪水群落以β-变形菌为主（占细菌总数的三分之一），而沉积物群落主要由β-变形菌和纤维杆菌/酸杆菌组的成员组成（各占细菌的约25%）。从水样细菌中获得的序列表明存在典型的世界性淡水生物。溪流和土壤样品之间共享的TGGE条带，以及溪流样品细菌中发现的与土壤细菌相关的序列，表明溪流和土壤栖息地中都存在一些物种。细菌群落组成的变化与沿溪流的地理距离相关，但在不同溪流和河流的比较中，群落组成仅与环境条件相关。
