Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai 200438, People's Republic of China.
Environmental Engineering, Guangdong Technion Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong 515063, People's Republic of China.
Sci Total Environ. 2021 May 10;768:144993. doi: 10.1016/j.scitotenv.2021.144993. Epub 2021 Jan 8.
The recently discovered complete ammonia oxidizers (comammox), which are ubiquitous in various natural and artificial ecosystems, have led to a paradigm shift in our understanding of aerobic nitrification. The coastal salt marsh covered by various plant species is an important ecosystem to link nitrogen cycles of terrestrial and marine environments; however, the distribution and structure of comammox in such ecosystems have not been clearly investigated. Here, we applied quantitative PCR and partial nested-PCR to investigate the abundance and community composition of comammox in salt marsh sediment samples covered by three plant types along the southern coastline of China. Our results showed a predominance of comammox clade A in majority of the samples, suggesting their ubiquity and the important role they play in nitrification in salt marsh ecosystems. However, variations by the sites were found when comparing the abundance of subclades of comammox clade A. Redundancy analysis demonstrated a coexistence pattern by comammox clade A.1 with ammonia-oxidizing archaea and comammox clade A.2 with canonical ammonia-oxidizing bacteria, indicating their differences in potential niche preference. However, the abundance of comammox clade B was lower than that of comammox clade A and other ammonia oxidizers in most samples. Moreover, pH and salinity were found to be the most significant factors affecting comammox community structures, suggesting their roles in driving niche partitioning of comammox, whereas plant types did not show a significant effect on the comammox community structure. Our study provided insights into the abundance, community diversity, and niche partitions of comammox, broadening the current understanding of the relationship of comammox with other ammonia oxidizers in salt marsh ecosystems.
最近发现的完全氨氧化菌（comammox）广泛存在于各种自然和人工生态系统中，这导致了我们对好氧硝化作用的理解发生了范式转变。被各种植物物种覆盖的沿海盐沼是连接陆地和海洋环境氮循环的重要生态系统；然而，这种生态系统中 comammox 的分布和结构尚未得到明确的研究。在这里，我们应用定量 PCR 和部分嵌套 PCR 技术，调查了中国南部海岸线三种植物类型覆盖的盐沼沉积物样本中 comammox 的丰度和群落组成。我们的结果表明，大多数样本中 comammox 分支 A 占主导地位，这表明它们在盐沼生态系统中的硝化作用中普遍存在且发挥着重要作用。然而，当比较 comammox 分支 A 的亚分支丰度时，发现了不同地点之间的差异。冗余分析表明 comammox 分支 A.1 与氨氧化古菌共存，comammox 分支 A.2 与典型的氨氧化细菌共存，这表明它们在潜在的生态位偏好上存在差异。然而，在大多数样本中，comammox 分支 B 的丰度低于 comammox 分支 A 和其他氨氧化菌。此外，发现 pH 值和盐度是影响 comammox 群落结构的最重要因素，这表明它们在驱动 comammox 的生态位分离中发挥作用，而植物类型对 comammox 群落结构没有显著影响。我们的研究提供了对 comammox 的丰度、群落多样性和生态位划分的深入了解，拓宽了目前对 comammox 与盐沼生态系统中其他氨氧化菌关系的理解。
