An overlooked nitrogen loss linked to anaerobic ammonium oxidation in estuarine sediments in China

Abstract

Purpose Despite its importance, anammox (anaerobic ammonium oxidation) in estuarine sediment systems remains poorly understood, particularly at the continental scale. This study aimed to understand the abundance, diversity, and activity of anammox bacteria and to determine the main factors influencing the anammox process in estuarine sediments in China. Materials and methods Estuarine sediments were collected from 18 estuaries spanning over 4000 km. Experiments using an 15 N-tracer, quantitative PCR, and clone library construction were used to determine the activity, abundance, and diversity of anammox bacteria. The impact of environmental factors on anammox processes was also determined.Results and discussion The abundance of the anammoxspecific hydrazine synthase (hzsB) gene ranged from 1.8 × 10 5 ± 3.4 × 10 4 to 3.6 × 10 8 ± 7.5 × 10 7 copies g −1 dw. Candidatus Scalindua, Brocadia, Kuenenia, Jettenia, and two novel unidentified clusters were detected, with Scalindua dominating the anammox population. Additionally, the abundances of Scalindua, Kuenenia, and Brocadia were found to be significantly correlated with latitude. The anammox rates ranged from 0.29 ± 0.15 to 13.68 ± 3.98 nmol N g −1 dw h −1 and contributed to 2.39-82.61% of total N 2 production. Pearson correlation analysis revealed that the anammox rate was positively correlated with total nitrogen, total carbon, and temperature, and was negatively correlated with dissolved oxygen (DO). The key factors influencing the hzsB gene abundance were ammonium concentration, salinity, and DO. Ammonium concentration, pH, temperature, and latitude were main variables shaping the anammox-associated bacterial community. Conclusions Our results suggested that anammox bacteria are ubiquitous in coastal estuaries in China and underline the importance of anammox resulting in N loss at a continental scale.

Anaerobic Ammonium Oxidation in Acidic Red Soils

“…It can be speculated that higher TN concentration may provide an environment favorable for the distribution and growth of anammox bacteria ( Shen et al, 2016 ). In line with other studies ( Metz et al, 2003 ; Etchebehere and Tiedje, 2005 ; Yang et al, 2017 ), a positive correlation between anammox activity and abundance ( hzsB or 16S rRNA gene) was not observed. These results indicated that anammox rates are limited not by the presence of the population capable of anammox but by the availability of or as substrate.…”

“…Candidatus Scalindua was almost the only genus found in marine sediments, such as South China Sea ( Hong et al, 2011a ), Bohai Sea ( Dang et al, 2013 ), and Arabian Sea ( Woebken et al, 2008 ). In contrast to marine environments, all of these genera of anammox bacteria have been detected in soil ecosystems ( Wang et al, 2015 ; Yang et al, 2017 ). Zhu et al (2011) found that the 16S rRNA gene sequence of fertilized paddy soil were related to four different genera of anammox bacteria.…”

Diversity and Distribution of Anaerobic Ammonium Oxidation Bacteria in Hot Springs of Conghua, China

“…Previous studies have shown that many different environmental factors can affect anammox bacterial diversity and distribution. For example, temperature was a key environmental factor shaping the distribution and diversity of anammox bacteria in the coastal estuaries of China ( Yang et al, 2017 ). Organic carbon influenced the distribution of anammox bacteria in Qiantang River sediments ( Hu et al, 2012 ) and Yangtze estuary marsh sediment ( Hou et al, 2013 ).…”

Wide distribution of anaerobic ammonium‐oxidizing bacteria in the water column of the South China Sea: Implications for their survival strategies

“…However, Ca . Brocadia possesses metabolic diversity and could make better use of organic compounds for energy than most other anammox bacteria (Gori, Tringe, Kartal, Marchiori, & Jetten, 2011; Yang et al, 2017). This metabolic diversity may explain why Ca .…”