Shift of anammox bacterial community structure along the Pearl Estuary and the impact of environmental factors

Abstract

Anaerobic ammonium oxidation (anammox) plays an important role in the marine nitrogen cycle. The Pearl Estuary, a typical subtropical estuary characterized by hypoxia upstream and high loads of organic matter and inorganic nutrients caused by anthropogenic activities, has received extensive attention.

Evolution of the sink and source of dissolved inorganic nitrogen with salinity as a tracer during summer in the Pearl River Estuary

“…However, observed dissolved oxygen in surface water samples in the PRE were 6 mg L −1 (data not shown). Anammox bacteria appeared in the water column which did not reach hypoxia in the PRE, and anammox bacteria mainly originated from land soil and wastewater in upstream sites45. Denitrification was regarded as a process competing with algal uptake for removal of nitrate from the water column in Chesapeake Bay10.…”

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

“…This N removal process, which oxidizes ammonium (NH 4 + ) via reducing nitrite (NO 2 ‐ ) to form N 2 under anaerobic environments [ Mulder et al ., ], is known to be mediated by chemolithoautotrophic bacteria belonging to the phylum Planctomycetes [ Strous et al ., ; Kartal et al ., ; Jetten et al ., ]. To date, five anammox bacterial genera have been recognized, which include Candidatus Kuenenia , Candidatus Brocadia , Candidatus Scalindua , Candidatus Anammoxoglobus , and Candidatus Jettenia [ Strous et al ., ; Schmid et al ., ; Kartal et al ., ; Quan et al ., ], and all these genera have been reported to exist in estuarine and coastal habitats [ Dale et al ., ; Fu et al ., ]. Although the process of anammox is an important pathway for removing N from estuarine and coastal environments [ Dale et al ., ; Hou et al ., ; Naeher et al ., ], little is known about how community dynamics and activity of anammox bacteria shift along the estuarine salinity gradient.…”

“…Salinity has been implicated as a key factor regulating anammox bacterial community composition [ Dale et al ., ; Fu et al ., ] and activity [ Rich et al ., ; Koop‐Jakobsen and Giblin , ], as it plays an important role in controlling the availability of N substrates in sediments [ Boynton and Kemp , ; Bernhard et al ., ] and/or different anammox bacterial genera might favor different salinity niches [ Fu et al ., ]. In estuarine and coastal environments, the spatially and seasonally varying mixtures of freshwater and seawater generally create a steep salinity gradient and thus presents a unique environment to refine our understanding of salinity effects on the anammox process.…”

Alternative device for ANAMMOX/denitrification rate assessment using manometric method

“…As it turned out, Anammox microorganisms are responsible for 30-70% of fixed nitrogen removal from marine environment and have ability to survive in a wide range of environments, also including activated sludge [7,8]. In general, Anammox is an anaerobic multi-stage process: nitrite (NO 2 -) is reduced to nitric oxide (NO) that reacts with ammonium (NH 4 + ) producing hydrazine (N 2 H 4 ), which is oxidized to nitrogen gas (N 2 ) [9].…”