Shifts in the community structure and activity of anaerobic ammonium oxidation bacteria along an estuarine salinity gradient

Abstract

Anaerobic ammonium oxidation (anammox) is a major microbial pathway for nitrogen (N) removal in estuarine and coastal environments. However, understanding of anammox bacterial dynamics and associations with anammox activity remains scarce along estuarine salinity gradient. In this study, the diversity, abundance, and activity of anammox bacteria, and their potential contributions to total N 2 production in the sediments along the salinity gradient (0.1-33.8) of the Yangtze estuarine and coastal zone, were studied using 16S rRNA gene clone library, quantitative polymerase chain reaction assay, and isotope-tracing technique. Phylogenetic analysis showed a significant change in anammox bacterial community structure along the salinity gradient (P < 0.01), with the dominant genus shifting from Brocadia in the freshwater region to Scalindua in the open ocean. Anammox bacterial abundance ranged from 3.67 × 10 5 to 8.22 × 10 7 copies 16S rRNA gene g À1 and related significantly with salinity (P < 0.05). The anammox activity varied between 0.08 and 6.46 nmol N g À1 h À1 and related closely with anammox bacterial abundance (P < 0.01). Contributions of anammox activity to total N loss were highly variable along the salinity gradient, ranging from 5 to 77% and were significantly negatively correlated with salinity (P < 0.

Anaerobic Ammonium Oxidation in Acidic Red Soils

“…The abundance of anammox bacteria ranged from 6.20 × 10 5 to 1.81 × 10 9 hzsB copies/g and 4.81 × 10 6 to 4.54 × 10 8 (anammox bacterial 16S rRNA gene), which fall within the ranges reported in Pearl River Estuary (1.4–20 × 10 8 hzsB copies/g; Wang et al, 2012 ), Yangtze Estuary (3.67–822 × 10 5 16S rRNA copies/g; Zheng et al, 2016 ), and paddy soils (0.7–1.4 × 10 7 hzs copies/g; Nie et al, 2015 ). Anammox bacterial abundances in red soils were confirmed by means of the anammox hzsB gene and 16S rRNA gene ( Figure 3 ), and abundances of these two target genes correlated ( r = 0.818, P < 0.001, n = 10).…”

Spatiotemporal distribution of bacterial dimethylsulfoniopropionate producing and catabolic genes in the Changjiang Estuary

“…The Changjiang River, also known as the Yangtze River, is the longest river in the Euro‐Asia continent, which plays an important role in global biogeochemical cycling (Hou et al ., 2008). Nutrients carried by the river are essential sources for phytoplankton primary production, which influence the bacterial community (Zhou et al ., 2007), as does the hydrological characteristics, especially the salinity gradient in different seasons (Zheng et al ., 2016).…”

Nitrogen Losses in Sediments of the East China Sea: Spatiotemporal Variations, Controlling Factors, and Environmental Implications

“…Benthic sediment of continental shelf acts as a large sink for reactive N, and thus plays an important role in N biogeochemical cycle (Song et al, ; Trimmer & Nicholls, ). Sandy sediments cover about 70% of the continental margin (Bale et al, ; Vance‐Harris & Ingall, ) and may play a potential sink for available N. However, most of the previous studies about sediment N‐loss pathways within the ECS have concentrated on the Yangtze Estuary (Deng et al, ; Zheng et al, ) or fine‐grained sediments from sparse sampling sites on the shelf (Song et al, ). Therefore, understanding of sediment denitrification, anammox, and N 2 O production remains limited in the ECS at a large spatial scale.…”