Biology Centre AS CR, Hydrobiological Institute,Ceské Budejovice, Czech Republic.
Appl Environ Microbiol. 2010 Feb;76(3):631-9. doi: 10.1128/AEM.02203-09. Epub 2009 Nov 30.
The distribution of the phylogenetically narrow R-BT065 cluster (Betaproteobacteria) in 102 freshwater lakes, reservoirs, and various ponds located in central Europe (a total of 122 samples) was examined by using a cluster-specific fluorescence in situ hybridization probe. These habitats differ markedly in pH, conductivity, trophic status, surface area, altitude, bedrock type, and other limnological characteristics. Despite the broad ecological diversity of the habitats investigated, the cluster was detected in 96.7% of the systems, and its occurrence was not restricted to a certain habitat type. However, the relative proportions of the cluster in the total bacterioplankton were significantly lower in humic and acidified lakes than in pH-neutral or alkaline habitats. On average, the cluster accounted for 9.4% of the total bacterioplankton (range, 0 to 29%). The relative abundance and absolute abundance of these bacteria were significantly and positively related to higher pH, conductivity, and the proportion of low-molecular-weight compounds in dissolved organic carbon (DOC) and negatively related to the total DOC and dissolved aromatic carbon contents. Together, these parameters explained 55.3% of the variability in the occurrence of the cluster. Surprisingly, no clear relationship of the R-BT065 bacteria to factors indicating the trophic status of habitats (i.e., different forms of phosphorus and chlorophyll a content) was found. Based on our results and previously published data, we concluded that the R-BT065 cluster represents a ubiquitous, highly active segment of bacterioplankton in nonacidic lakes and ponds and that alga-derived substrates likely form the main pool of substrates responsible for its high growth potential and broad distribution in freshwater habitats.
通过使用特定于聚类的荧光原位杂交探针，研究了分布在中欧的 102 个淡水湖泊、水库和各种池塘（共 122 个样本）中的系统发育狭窄的 R-BT065 聚类（β变形菌）。这些栖息地在 pH 值、电导率、营养状态、表面积、海拔、基岩类型和其他湖泊学特征方面差异显著。尽管所研究的栖息地具有广泛的生态多样性，但该聚类在 96.7%的系统中被检测到，并且其出现不受特定栖息地类型的限制。然而，在富营养化和酸化的湖泊中，该聚类在总浮游细菌中的相对比例明显低于 pH 值中性或碱性生境中的相对比例。平均而言，该聚类占总浮游细菌的 9.4%（范围为 0 至 29%）。这些细菌的相对丰度和绝对丰度与较高的 pH 值、电导率以及溶解有机碳（DOC）中低分子量化合物的比例呈显著正相关，与总 DOC 和溶解芳香族碳含量呈负相关。这些参数共同解释了聚类出现的 55.3%的可变性。令人惊讶的是，未发现 R-BT065 细菌与指示栖息地营养状态的因素（即不同形式的磷和叶绿素 a 含量）之间存在明显的关系。根据我们的结果和以前发表的数据，我们得出结论，R-BT065 聚类代表了非酸性湖泊和池塘中浮游细菌的普遍存在、高度活跃的部分，藻类衍生的底物可能构成了其高生长潜力和在淡水生境中广泛分布的主要底物池。
