Ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) play crucial roles in ammonia nitrogen degradation in freshwater lake sediment. However, studies on ammonia-oxidizing microorganisms (AOM) in vertical sediment are still limited, especially with respect to the quantitative analysis of the vertical distribution of active AOM at the RNA level. Herein, by researching the AOM in a 75 cm vertical sediment from Lake Taihu, we found that although the total abundance of AOB throughout the whole vertical sediment surpassed that of AOA, active AOA had a closer correlation with the potential nitrification rate than active AOB. The active transcription abundance of AOM generally decreased with increasing depth, especially for AOA, while that of AOB decreased slightly. Compared to active transcription, the total abundance of AOM varied little. The community structures of AOA and AOB changed significantly with increasing depth, and Group I.1a and Nitrosomonas were the predominant clusters, respectively. Ultimately, our study demonstrated that research methods based on the RNA level can accurately reflect the vertical variation in AOM.

氨氧化古细菌（AOA）和氨氧化细菌（AOB）在淡水湖沉积物中氨氮降解中起关键作用。但是，垂直沉积物中氨氧化微生物（AOM）的研究仍然有限，特别是在RNA水平上对活性AOM垂直分布的定量分析方面。在本文中，通过研究太湖75厘米垂直沉积物中的AOM，我们发现尽管整个垂直沉积物中AOB的总丰度超过了AOA，但活性AOA与潜在硝化率的关系比活性AOB更为紧密。AOM的活性转录丰度通常随深度的增加而降低，尤其是AOA，而AOB的活性转录丰度则略有下降。与主动转录相比，AOM的总丰度变化很小。亚硝酸盐分别是主要的簇。最终，我们的研究表明，基于RNA水平的研究方法可以准确反映AOM的垂直变化。