In natural habitats, the diversity of anaerobic ammonia-oxidizing (anammox) bacteria could be affected by multiple environmental variables. In this study, we investigated the distribution of the anammox bacterial community in surface sediment from the Dongjiang River (riverine sediment, DJ) to the Pearl River Estuary (estuarine sediment, PRE) and then to the South China Sea (coastal sediment, SCS). The results revealed evident differences in the structural diversity of anammox bacteria in three different habitats. Candidatus Brocadia accounted for approximately 90% of the total anammox bacteria in DJ, conversely, Ca. Scalindua dominated in the SCS. Nevertheless, Ca. Scalindua, Ca. Brocadia and Ca. Kuenenia coexisted in the PRE. The qPCR results indicated that anammox bacterial 16S rRNA gene abundance ranged from 2.23 × 10⁵ to 1.19 × 10⁷ copies g⁻¹ of wet weight, but no significant correlation was found between the abundances and environmental variables (p > 0.05). The relative abundances of Ca. Brocadia gradually decreased with increasing salinity, and Ca. Scalindua showed the opposite trend, suggesting that salinity was a crucial factor in sculpturing the community composition of anammox bacteria in natural environments. Ca. Brocadia should be able to live in freshwater ecosystems, but it can also tolerate a certain level of salinity. Ca. Scalindua was halophilic anammox bacterium and exists only in saline environments. Ca. Kuenenia could adapt to a wide range of salinity and preferred to live in high DIN level conditions according to our search. The distribution pattern of anammox bacteria may be the result of microbial migration and long-term adaptation to salinity.

在自然栖息地，厌氧氨氧化 (anammox) 细菌的多样性可能受到多种环境变量的影响。在这项研究中，我们调查了从东江（河流沉积物，DJ）到珠江口（河口沉积物，PRE）再到南海（沿海沉积物，SCS）的表层沉积物中厌氧氨氧化细菌群落的分布. 结果表明，三个不同生境中厌氧氨氧化细菌的结构多样性存在明显差异。Candidatus Brocadia 约占 DJ 中厌氧氨氧化细菌总数的 90%，相反，Ca。斯卡林杜亚在南海占主导地位。尽管如此，Ca . Scalindua，钙。Brocadia 和Ca. Kuenenia 共存于 PRE。qPCR结果表明厌氧氨氧化细菌16S rRNA基因丰度范围为湿重的2.23×10 ⁵至1.19×10 ⁷拷贝g ^-1，但丰度与环境变量之间没有显着相关性（p  > 0.05）。Ca的相对丰度。Brocadia 随着盐度的增加而逐渐减少，Ca。Scalindua 显示出相反的趋势，表明盐度是塑造自然环境中厌氧氨氧化细菌群落组成的关键因素。钙。Brocadia 应该能够生活在淡水生态系统中，但它也可以忍受一定程度的盐度。钙。Scalindua 是嗜盐厌氧氨氧化菌，只存在于盐碱环境中。钙。根据我们的搜索，Kuenenia 可以适应广泛的盐度，并且更喜欢生活在高 DIN 水平的条件下。厌氧氨氧化菌的分布格局可能是微生物迁移和长期适应盐分的结果。