Ammonia Oxidizers in High-Elevation Rivers of the Qinghai-Tibet Plateau Display Distinctive Distribution Patterns

Abstract

Ammonia-oxidizing bacteria (AOB) and archaea (AOA) as well as comammox catalyze ammonia oxidation. The distribution and biogeography of these ammonia oxidizers might be distinctive in high-elevation rivers, which are generally characterized by low temperature and low ammonium concentration but strong solar radiation; however, these characteristics have rarely been documented. This study explored the abundance, community, and activity of ammonia oxidizers in the overlying water of five rivers in the Qinghai-Tibet Plateau (QTP). Potential nitrification rates in these rivers ranged from 5.4 to 38.4 nmol N liter−1 h−1, and they were significantly correlated with ammonium concentration rather than temperature. Comammox were found in 25 of the total 28 samples, and they outnumbered AOA in three samples. Contrary to most studied low-elevation rivers, average AOB amoA gene abundance was significantly higher than that of AOA, and AOB/AOA ratios increased with decreasing water temperature. The Simpson index of the AOA community increased with elevation (P < 0.05), and AOA and AOB communities exhibited high dissimilarities with low-elevation rivers. Cold-adapted (Nitrosospira amoA cluster 1, 33.6%) and oligotrophic (Nitrosomonas amoA cluster 6a, 31.7%) groups accounted for large proportions in the AOB community. Suspended sediment concentration exerted significant effects on ammonia oxidizer abundance (r > 0.56), and owing to their elevational variations in source and concentration, suspended sediments facilitated distance-decay patterns for AOA and AOB community similarities. This study demonstrates distinctive biogeography and distribution patterns for ammonia oxidizers in high-elevation rivers of the QTP. Extensive research should be conducted to explore the role of these microbes in the nitrogen cycle of this zone. IMPORTANCE Ammonia-oxidizing archaea (AOA) and bacteria (AOB) as well as comammox contribute to ammonia oxidation, which plays significant roles in riverine nitrogen cycle and N2O production. Source regions of numerous rivers in the world lie in high-elevation zones, but the abundance, community, and activity of ammonia oxidizers in rivers in high-elevation regions have rarely been investigated. This study revealed distinctive distribution patterns and community structures for ammonia oxidizers in five high-elevation rivers of the Qinghai-Tibet Plateau, and the individual and combined effects of low temperature, low nutrients, and strong solar radiation on ammonia oxidizers were elucidated. The findings of this study are helpful to broaden our knowledge on the biogeography and distribution pattern of ammonia oxidizers in river systems. Moreover, this study provides some implications to predict the performance of ammonia oxidizers in high-elevation rivers and its variations under global climate warming.

Microbial Communities in Vermiculation Deposits from an Alpine Cave

“…The high proportion of bacteria over archaea found in the vermiculations is consistent with previous reports indicating that in terrestrial ecosystems nitrate stimulates the activity of ammonia-oxidizing bacteria, but not that of archaea (Meinhardt et al, 2018). In addition, Zhang et al (2019a) reported that bacterial amoA gene abundance was significantly higher than that of archaea due to the activity of cold adapted Nitrosospira in rivers from the Qinghai-Tibet Plateau. In this context, Zhang et al (2019b) showed that soil microbial communities were adapted to high nitrogen levels, strengthening the function of ammonia oxidation in order to deplete the excess of nitrogen.…”

Distribution and Diversity of Comammox Nitrospira in Coastal Wetlands of China

“…Recent studies of ammonia oxidizing microbial communities based on amoA genes revealed that relative proportions of comammox Nitrospira , AOB and AOA are highly variable across environmental matrixes including both natural and engineered systems ( Table 1 ). While in most ecosystems (e.g., river water, grassland, agricultural and paddy soil) AOA or AOB were the dominating organisms ( Kits et al, 2017 ; Zhang et al, 2019 ), comammox Nitrospira were found to mainly dominate in engineered systems ( Bartelme et al, 2017 ; Tatari et al, 2017 ), but also in some natural environments, such as specific freshwater lakes ( Shi et al, 2020 ) or the river water and sediments of the Yangtze River ( Liu et al, 2020 ). Contrary, no marine comammox organisms have been identified so far.…”

Candidatus Nitrosopolaris, a genus of putative ammonia-oxidizing archaea with a polar/alpine distribution

“…Nitrosopolaris MAGs are most closely related (98.9–99.7% nucleotide similarity) to uncultured sequences from Antarctic soil (MH318339 and MH318307), grassland soil in Iceland (JQ403917 and JQ403913), and the Tibetan Plateau (GQ143258, GQ143220, GQ143135, KF004058, and MK987234) (Daebeler et al ., 2012; Xie et al ., 2014; Wang et al ., 2019; Zhang et al ., 2019) (Fig. 3b) .…”