水位变化对消落带氨氧化微生物丰度和多样性的影响

南水北调来水进入密云水库将直接引起水库水位上涨,这必将影响消落带土壤中氨氧化微生物的丰度和多样性,从而影响消落带中氮循环过程.采用分子生物学方法,探讨了水位变化对消落带氨氧化细菌(AOB)和古菌(AOA)的生物多样性和丰度的影响.Real-time PCR结果显示,2015年9月消落带岸上/水陆界面土壤和沉积物中AOA和AOB的丰度范围分别为1.00×10~7~3.91×10~7copies·g~(-1)和5.49×10~6~9.77×10~6copies·g~(-1).2015年11月水位比9月上升3 m,淹没区土壤/沉积物中AOA和AOB的丰度范围分别为5.80×106~1.56×10~7copies·g~(-1)和2.14×10~6~4.40×106copies·g~(-1),比被淹没前有所下降,但AOA的丰度始终高于AOB,说明AOA比AOB更适合在低氨氮的消落带环境中生长,并且更能适应低氧环境.水位上升3 m后,水陆交界面土壤中AOA和AOB的多样性均有所增加,而在沉积物中多样性减少.水位上涨之前,AOA大多数OTU属于Nitrososphaera、Nitrosopumilus,而水位上涨之后,大多数OTU归属于土壤簇Nitrososphaera,即在低氧消落带环境中土壤簇Nitrososphaera为优势AOA菌.对于AOB,水陆交界面土壤和沉积物中Nitrosopira和Nitrosomonas分别在氨氧化过程中发挥作用.

The impact of water level change on the abundance and diversity of ammonia oxidizing bacteria(AOB) and ammonia oxidizing archaea(AOA) in water-fluctuating zone

South-to-North Water Diversion directly lead to the rise of water level of the Miyun reservoir, which would change the abundance and the diversity of ammonia oxidizing microorganism, and then affect the nitrogen cycling in water-fluctuating zone. The impact of water level change on the abundance and diversity of ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) in water-fluctuating zone were analyzed in this study. Quantitative Real-time PCR results show that the copy numbers of AOA and AOB varied from 1.00×10⁷~3.91×10⁷ to 5.49×10⁶~9.77×10⁶ copies·g^-1 respectively in soil of landward and land-water interface, sediment in water-fluctuating zone in September of 2015. In November of 2015 water level had risen by 3 m relatively to September of the same year, the copy numbers of AOA and AOB varied from 5.80×10⁶~1.56×10⁷ to 2.14×10⁶~4.40×10⁶copies·g^-1 respectively in flooded soil and sediment, which were lower than non-flooded soil and sediment. However, the copy numbers of AOA were always higher than AOB. This indicated AOA had and better adaptability in water-fluctuating zone where both ammonia and oxygen levels were low. After water level elevated to 3 m, the diversity of AOA and AOB increased in soil of land-water interface, but decreased in sediment. Before the rise of water level, most OTUs in AOA belonged to Nitrososphaera and Nitrosopumilus. After the rise of water level, most OTUs belonged to soil cluster Nitrososphaera. Namely, soil cluster Nitrososphaera predominated in low oxygen containing water-fluctuating zone. For AOB, Nitrosopira and Nitrosomonas played an important role in ammonia oxidation process respectively in soil of land-water interface and sediment.