Candidatus Brocadia and Candidatus Kuenenia predominated in anammox bacterial community in selected Chinese paddy soils

Abstract

Purpose Anammox bacteria have been widely investigated in both natural aquatic habitats and wastewater treatment reactors. However, their distribution in agricultural ecosystems which receive high reactive nitrogen input is hardly known. This study aims to examine the distribution and diversity of anammox bacteria in different Chinese paddy soils and along soil profile horizons. Materials and methods DNA was extracted from paddy soils which were collected from ten sites and along four soil depth horizons (0-20, 20-40, 40-60, 60-80 cm). Community structure and diversity of the anammox bacteria were analyzed using cloning and sequencing methods by targeting 16S ribosomal RNA (rRNA) genes. Quantitative PCR was conducted to study the abundance of anammox hzsB genes. Results and discussion Anammox bacterial 16S rRNA genes were not detected in most of the surface soil profile layers but present in all subsurface and deep horizons. Two genera, Candidatus Brocadia and Candidatus Kuenenia, were the only groups detected, and the former was predominant in tested soils. A site-specific distribution pattern of anammox bacteria and significant relationship between anammox bacteria community composition and soil pH and ammonium concentration were observed. The abundance of anammox bacteria hzsB gene ranged from 3.78×10 4 to 1.64×10 7 per gram of dry soil in all soils and significantly varied along the soil profile horizons. Conclusions Anammox bacteria were widely distributed in paddy soils, especially in subsurface and profile depth horizons. Candidatus Brocadia and Candidatus Kuenenia were the dominating anammox groups in the tested soils, and the two genera showed a site-specific distribution pattern across large Chinese paddy soil areas and along soil depth profiles.

The phenological stage of rice growth determines anaerobic ammonium oxidation activity in rhizosphere soil

“…Similar to previous reports, Candidatus Brocadia dominated in this paddy soils fields (Bai et al, 2015;Yang et al, 2015). Bacteria of this genus harbor diverse metabolism (Gori et al, 2011), with the ability to use short-chain organic acids as electron donors instead of NH 4 þ , making it highly adaptable.…”

Activity, abundance and community structure of anammox bacteria along depth profiles in three different paddy soils

“…4). In many previous studies, the detection frequency of Candidatus Jettenia was much lower in comparison to Candidatus Brocadia and Kuenenia, and was even undetectable in some paddy soils (Bai et al, 2015;Yang et al, 2015). However, it was also shown that Candidatus Jettenia occupied a large portion of anammox bacterial Table 2 The detected OTUs and diversity indices of anammox bacteria based on the clone library analysis of 16S rRNA genes by 3% cutoff, and the copy numbers of hzsB genes along depth profiles of three paddy soils.…”

“…Therefore, it is not surprising that Candidatus Scalindua was absent but Candidatus Brocadia and Kuenenia were predominant in paddy soils in this study. Recent investigations have also demonstrated the wide prevalence of these two genera in paddy soils (Bai et al, 2015) and dry agricultural soils (Shen et al, 2013) across broad areas of China. Observations from laboratory-scale experiments indicated that Candidatus Brocadia had relatively higher tolerance to O 2 and a higher growth rate (Oshiki et al, 2011).…”

“…Furthermore, anammox bacteria are considered to be habitat-specific with certain groups observed to be dominant in distinct environments (Humbert et al, 2010). For instance, Candidatus Scalindua was mainly discovered in marine ecosystems (Penton et al, 2006;Rich et al, 2008;Li et al, 2010), while Candidatus Brocadia and Kuenenia were more predominant in agricultural soils (Shen et al, 2013;Bai et al, 2015). However, a recent study reported the dominance of Candiatus Scalindua in paddy soils in Northeast China, which raised the question of a heterogeneous distribution of anammox bacteria in different soil types (Wang and Gu, 2013).…”

“…Anammox bacteria were also detected in environments with a salinity gradient from freshwater to marine ecosystems . Several studies have shown the existence of anammox in paddy soils (Zhu et al, 2011b;Wang and Gu, 2013), and environmental factors such as pH and NH 4 þ were found to be significantly correlated with the community structure of anammox bacteria (Bai et al, 2015;Yang et al, 2015). However, most of these studies concentrated more on the molecular ecology characteristics of anammox bacteria, relatively little is known about the potential linkage between anammox activity and bacterial community and the determining environmental factors.…”