Department of Microbial Ecology, Netherlands Institute of Ecology, P.O. Box 1299, Maarssen 3600 BG, the Netherlands.
Appl Environ Microbiol. 2010 Mar;76(6):1813-21. doi: 10.1128/AEM.01917-09. Epub 2010 Jan 22.
In addition to the benthic and pelagic habitats, the epiphytic compartment of submerged macrophytes in shallow freshwater lakes offers a niche to bacterial ammonia-oxidizing communities. However, the diversity, numbers, and activity of epiphytic ammonia-oxidizing bacteria have long been overlooked. In the present study, we analyzed quantitatively the epiphytic communities of three shallow lakes by a potential nitrification assay and by quantitative PCR of 16S rRNA genes. On the basis of the m(2) of the lake surface, the gene copy numbers of epiphytic ammonia oxidizers were not significantly different from those in the benthic and pelagic compartments. The potential ammonia-oxidizing activities measured in the epiphytic compartment were also not significantly different from the activities determined in the benthic compartment. No potential ammonia-oxidizing activities were observed in the pelagic compartment. No activity was detected in the epiphyton of Chara aspera, the dominant submerged macrophyte in Lake Nuldernauw in The Netherlands. The presence of ammonia-oxidizing bacterial cells in the epiphyton of Potamogeton pectinatus was also demonstrated by fluorescent in situ hybridization microscopy images. By comparing the community composition as assessed by the 16S rRNA gene PCR-denaturing gradient gel electrophoresis approach, it was concluded that the epiphytic ammonia-oxidizing communities consisted of cells that were also present in the benthic and pelagic compartments. Of the environmental parameters examined, only the water retention time, the Kjeldahl nitrogen content, and the total phosphorus content correlated with potential ammonia-oxidizing activities. None of these parameters correlated with the numbers of gene copies related to ammonia-oxidizing betaproteobacteria.
除了底栖和浮游栖息地外，浅水湖泊中的附生植物生境也为细菌氨氧化群落提供了小生境。然而，附生氨氧化细菌的多样性、数量和活性长期以来一直被忽视。在本研究中，我们通过潜在硝化测定和 16S rRNA 基因的定量 PCR 对三个浅水湖的附生群落进行了定量分析。基于湖泊表面的 m(2)，附生氨氧化菌的基因拷贝数与底栖和浮游区室没有显著差异。在附生区室中测量的潜在氨氧化活性也与在底栖区室中确定的活性没有显著差异。在浮游区室中没有观察到潜在的氨氧化活性。在荷兰 Nuldernauw 湖的优势沉水植物轮藻的附生生物中没有检测到氨氧化活性。通过荧光原位杂交显微镜图像也证明了鱼腥藻附生生物中存在氨氧化细菌细胞。通过比较 16S rRNA 基因 PCR-变性梯度凝胶电泳方法评估的群落组成，可以得出结论，附生氨氧化群落由也存在于底栖和浮游区室中的细胞组成。在所检查的环境参数中，只有水保留时间、凯氏氮含量和总磷含量与潜在氨氧化活性相关。这些参数均与与氨氧化β变形菌相关的基因拷贝数无关。
