Ammonia- and methane-oxidizing microorganisms in high-altitude wetland sediments and adjacent agricultural soils

Abstract

Ammonia oxidation is known to be carried out by ammonia-oxidizing bacteria (AOB) and archaea (AOA), while methanotrophs (methane-oxidizing bacteria (MOB)) play an important role in mitigating methane emissions from the environment. However, the difference of AOA, AOB, and MOB distribution in wetland sediment and adjacent upland soil remains unclear. The present study investigated the abundances and community structures of AOA, AOB, and MOB in sediments of a high-altitude freshwater wetland in Yunnan Province (China) and adjacent agricultural soils. Variations of AOA, AOB, and MOB community sizes and structures were found in water lily-vegetated and Acorus calamus-vegetated sediments and agricultural soils (unflooded rice soil, cabbage soil, and garlic soil and flooded rice soil). AOB community size was higher than AOA in agricultural soils and lily-vegetated sediment, but lower in A. calamus-vegetated sediment. MOB showed a much higher abundance than AOA and AOB. Flooded rice soil had the largest AOA, AOB, and MOB community sizes. Principal coordinate analyses and Jackknife Environment Clusters analyses suggested that unflooded and flooded rice soils had relatively similar AOA, AOB, and MOB structures. Cabbage soil and A. calamus-vegetated sediment had relatively similar AOA and AOB structures, but their MOB structures showed a large difference. Nitrososphaera-like microorganisms were the predominant AOA species in garlic soil but were present with a low abundance in unflooded rice soil and cabbage soil. Nitrosospira-like AOB were dominant in wetland sediments and agricultural soils. Type I MOB Methylocaldum and type II MOB Methylocystis were dominant in wetland sediments and agricultural soils. Moreover, Pearson's correlation analysis indicated that AOA Shannon diversity was positively correlated with the ratio of organic carbon to nitrogen (p < 0.05). This work could provide some new insights toward ammonia and methane oxidation in soil and wetland sediment ecosystems.

Distribution of ammonia-oxidizing archaea and bacteria in plateau soils across different land use types

“…A few previous studies showed the numerical dominance of AOA over AOB in plateau grassland soils, agricultural soils, and forest soils (Chen et al 2013;Ding et al 2014;Wang et al 2012;Yang et al 2014;Zheng et al 2014). In this study, AOA outnumbered AOB in most of the studied plateau soils, suggesting that AOA might play a more important role in ammonia oxidation.…”

“…Wang et al (2014a) revealed a marked difference in both AOA and AOB community composition in reed-planted riparian soil, bare riparian soil, and maize-planted agricultural soil. Yang et al (2014) also showed a large shift in both AOA and AOB community composition in rice, cabbage, and garlic soils in the Yunnan Plateau. Moreover, Zhao et al (2015) found that AOB community composition was more sensitive to the land use regimes than AOA, while Meyer et al (2014) suggested that, compared with AOB, AOA community composition was responsive to land use intensity.…”

“…Several previous studies indicated that soil AOA and AOB abundance could be influenced by land use type Qin et al 2013;Wang et al 2014a;Yang et al 2014).…”

“…A few recent studies showed a profound variation in the community diversity of AOA and AOB in different plateau soils (Ding et al 2014;Yang et al 2014;Zheng et al 2014), while the driver of AOA and AOB diversity in plateau soils remains elusive. Ding et al (2014) suggested that TN and OM content might be a key determinant of AOA community diversity in plateau soils.…”

“…A relatively strong ambient ultraviolet radiation might select for a distinctive plateau soil microbial community (Ding et al 2014). However, little is known about the abundance and structure of soil AOA and AOB communities in the Yunnan Plateau (Ding et al 2014;Yang et al 2014), and the key drivers governing their distribution in plateau soils remain unclear. Moreover, there are about 40 natural freshwater lakes in the Yunnan Plateau.…”