黑藻根际对沉积物中氨氧化细菌和古菌的影响

氨氧化反应对水生态系统氮循环和氮的去除有重要作用，沉水植物通过根系泌氧促进沉积物中硝化反应并对氨氧化细菌和古菌的分布产生影响。本研究以轮叶黑藻为实验对象，利用微电极研究沉积物-水界面的溶解氧变化，研究了黑藻根系对沉积物中氨氧化细菌和古菌数量的影响。结果表明，黑藻通过根系泌氧增加沉积物-水界面的溶解氧量和表层沉积物有氧层厚度，有氧层厚度增加了3 mm以上；种植黑藻后，根际沉积物中氨氧化细菌数量逐渐增加，氨氧化古菌数量前30天增加随后减少，氨氧化细菌与氨氧化古菌amoA基因拷贝数的比值由0.51增加到6.75，说明黑藻根际沉积物更适宜氨氧化细菌的生存。

Effect of Hydrilla verticillata rhizosphere on ammonia oxidizing bacteria and archaea in sediment

Ammonia oxidation plays an improtant role in the cycling and removal of nitrogen in aquatic ecosystems.Oxygen releases from the roots of macrophyte stimulates nitrification in the rhizosphere and thus affects the distribution of rhizosphere-associated ammonia-oxidizing bacteria (AOB) and archaea (AOA) in sediment.In the present study,microelectrodes and real-time PCR were used to investigate the changes in dissolved oxygen in sediment-water interface and quantities of AOA and AOB in sediment colonized with the submerged macrophyte Hydrilla verticillata.The results showed that H.verticillata increased the contents of dissolved oxygen in sediment-water interface and oxic layer thickness in sediment surface.More than 3 mm of oxic surface layer was found in vegetated sediment compared with unvegetated sediment.H.verticillata could increase the number of AOB,while the number of AOA increased at first 30 days but then gradually decreased to initial level.The ratios of the bacterial-to-archaeal amoA gene increased from 0.51 to 6.75 in the rhizosphere,indicating that the rhizosphere of H.verticillata provided conditions favoring enrichment of AOB.