生态修复水生植物根际氨氧化细菌的研究

Ammonia-Oxidizing Bacteria Community Composition at the Root Zones of Aquatic Plants after Ecological Restoration

为研究水生植被恢复对底泥氨氧化细菌(ammonia-oxidizing bacteria,AOB)种群的影响,选取在生态修复中广泛使用的4种水生植物,芦苇(Phragmites communis)、窄叶香蒲(Typha angustifoliaL.)、菹草(Potamogeton crispusL.)和荇菜(Limnanthemunnymphoides),采用最大可能数法(most probable number,MPN)计数AOB的数量,巢式聚合酶链式反应-变性梯度凝胶电泳(nestedpolymerase chain reaction-denaturing gradient gel electrophoresis,nested PCR-DGGE)及条带回收测序的方法分析AOB的主要种类.结果显示,水生植物根际AOB密度显著高于无水生植物的表层底泥,而芦苇(2.8×105cells/g)和菖蒲(4.3×105cells/g)又明显高于菹草(9.3×104cells/g)和荇菜(7.7×104cells/g).水生植物根际呈氧化环境,而NH4+的浓度低于无水生植物的对照区.DNA测序结果显示尽管不同植物根际AOB主要种类有所区别,但基本属于亚硝化单胞菌属(Nitrosomonas).此类微生物群落在水生植物根际的聚集对促进生态修复中N元素的循环具有重要作用.

To investigate the effects of aquatic plants on ammonia-oxidizing bacteria（AOB） at their root zones,four species of aquatic plants were selected,Phragmites communis,Typha angustifolia L.,Potamogeton crispus L.,and Limnanthemun nymphoides,which were widely used in ecological restorations.AOB in the samples were enumerated by most-probable-number（MPN） method.Nested polymerase chain reaction-denaturing gradient gel electrophoresis（PCR-DGGE） procedures were performed with ammonia oxidizer-selective primers.Main DGGE bands were excised from the gel and sequenced for phylogenetic affiliation.Results indicate that AOB densities are always higher at the root zones of emergent plants（Phragmites communis 2.8×10^5cells/g and Typha angustifolia L.4.3×10^5cells/g） than those of submerged and floating-leaved plant（Potamogeton crispus L.9.3×10^4cells/g and Limnanthemun nymphoides 7.7×10^4cells/g）.At the root zones,the oxidation-reduction potential is above zero and NH4^＋concentration is lower than it in the bare surface sediment.Fourteen major bands were recovered from the DGGE gel,re-amplified and sequenced.Although the identified bands have their respective similar sequences in GenBank,most of them are related to Nitrosomonas-like.This type of bacteria would play an important role of nitrogen cycle in lake sediment after ecological restoration.