Anaerobic Ammonium Oxidation in Acidic Red Soils.

Jiapeng Wu,Xiang He,Yiguo Hong,Yiben Li,Guangshi Chen,Xiaomei Wen,Lijing Jiao,Yaohao Hu,Xiaohan Liu,Tianzheng Huang,Shuai Chen

doi:10.3389/fmicb.2018.02142

Abstract

Anaerobic ammonium oxidation (anammox) has been proven to be an important nitrogen removal process in terrestrial ecosystems, particularly paddy soils. However, the contribution of anammox in acidic red soils to nitrogen loss has not been well-documented to date. Here, we investigated the activity, abundance, and distribution of anammox bacteria in red soils collected from nine provinces of Southern China. High-throughput sequencing analysis showed that Candidatus Brocadia dominates the anammox bacterial community (93.03% of sequence reads). Quantification of the hydrazine synthase gene (hzsB) and anammox 16S rRNA gene indicated that the abundance of anammox bacteria ranged from 6.20 × 106 to 1.81 × 109 and 4.81 × 106 to 4.54 × 108 copies per gram of dry weight, respectively. Contributions to nitrogen removal by anammox were measured by a 15N isotope-pairing assay. Anammox rates in red soil ranged from 0.01 to 0.59 nmol N g−1 h−1, contributing 16.67–53.27% to N2 production in the studied area, and the total amount of removed nitrogen by anammox was estimated at 2.33 Tg N per year in the natural red soils of southern China. Pearson correlation analyses revealed that the distribution of anammox bacteria significantly correlated with the concentration of nitrate and pH, whereas the abundance and activity of anammox bacteria were significantly influenced by the nitrate and total nitrogen concentrations. Our findings demonstrate that Candidatus Brocadia dominates anammox bacterial communities in acidic red soils and plays an important role in nitrogen loss of the red soil in Southern China.

Highlights

Anaerobic ammonium oxidation is a principal microbe-driven process that removes excess N from an ecosystem and oxidizes NH+4 with NO−2 or NO−3 to form N2 gas under anaerobic autotrophic condition (Mulder et al, 1995)
Anammox bacteria related to Candidatus Brocadia, Kuenenia, and two novel unidentified clusters were found to dominate in the 12 typical paddy soils collected in southern China (Yang et al, 2015)
Increasing evidences showed that anammox bacteria play a significant role in nitrogen loss in agricultural soils, paddy soils (Zhu et al, 2011; Wang and Gu, 2013; Wang et al, 2014; Nie et al, 2015; Yang et al, 2015)

Summary

Introduction

Anaerobic ammonium oxidation (anammox) is a principal microbe-driven process that removes excess N from an ecosystem and oxidizes NH+4 with NO−2 or NO−3 to form N2 gas under anaerobic autotrophic condition (Mulder et al, 1995). 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. Shen et al (2017) detected three genera of anammox bacteria by Illumina-based 16S rRNA gene sequencing in a vegetable field, including Candidatus Kuenenia, Brocadia, and Jettenia. Another study showed that anammox bacteria in rice paddy soils were consisted of mainly Candidatus Scalindua (Wang and Gu, 2013), which was regarded as the dominant genus in marine environments. There has been limited evidence for the existence and role of anammox bacteria in acidic and natural red soils

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Results

Conclusion