Effects of dam building on the occurrence and activity of comammox bacteria in river sediments and their contribution to nitrification.
Sci Total Environ
; 864: 161167, 2023 Mar 15.
Article
in En
| MEDLINE
| ID: mdl-36572300
ABSTRACT
The recent discovery of complete ammonia oxidizers (comammox) has fundamentally changed our understanding of nitrification. However, studies on the occurrence and activity of comammox bacteria and their contribution to nitrification remain unclear. Here, we investigated the abundance, activity, and diversity of comammox bacteria and their contribution to nitrification in sediments from dammed rivers in winter and summer. Our results indicated that comammox clade A was ubiquitous in all sediment samples and the community structure in comammox varied between the upper and lower reaches, but not on the time scale (winter and summer). Comammox activity in the dammed river sediments in summer was prominently higher than in winter (summer 1.08⯱â¯0.52; winter 0.197⯱â¯0.148â¯mgâ¯Nâ¯kg-1â¯day-1). Furthermore, the activity of comammox bacteria in summer appeared higher in the vicinity of the dammed river and in the Sanjiang estuary, which is located downstream of the dammed river. The activity of ammonia-oxidizing bacteria (AOB) (0.77⯱â¯0.478â¯mgâ¯Nâ¯kg-1â¯day-1) was higher compared to comammox (0.639⯱â¯0.588â¯mgâ¯Nâ¯kg-1â¯day-1) and ammonia-oxidizing archaea (AOA) (0.026⯱â¯0.022â¯mgâ¯Nâ¯kg-1â¯day-1) in both winter and summer. In terms of contribution to the nitrification process, AOB (winter 67.13⯱â¯12.21â¯%; summer 50.57⯱â¯16.14â¯%) outperformed comammox (winter 28.59⯱â¯12.51â¯%; summer 48.38⯱â¯16.62â¯%) and AOA (winter <7.39â¯%; summer <2.09â¯%). These findings indicated that the nitrification process in dammed river sediments was mainly dominated by AOB. Additionally, comammox activity was significantly affected by temperature and NH4+, suggesting that these variables were key determinants of the niche partitioning of comammox. Collectively, our findings provide novel perspectives into the widespread distribution and contribution of comammox to nitrification in dammed river ecosystems, thus broadening our understanding of the nitrification processes.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Betaproteobacteria
/
Nitrification
Language:
En
Journal:
Sci Total Environ
Year:
2023
Document type:
Article
Affiliation country:
China
Publication country:
HOLANDA
/
HOLLAND
/
NETHERLANDS
/
NL
/
PAISES BAJOS
/
THE NETHERLANDS