Transcriptionally active ammonia-oxidizing nitrifiers in a surface flow constructed wetland

Area of Science:

• Environmental Microbiology
• Wetland Ecology
• Biogeochemistry

Background:

• Ammonia-oxidizing nitrifiers (AON) are crucial for nitrogen removal in constructed wetlands (CWs).
• Understanding the diversity and environmental drivers of AON communities is vital for optimizing CW function.
• Previous studies highlight the need for reappraising AON communities in CWs.

Purpose of the Study:

• To investigate the active ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and comammox bacteria (CMX) communities in CW sediments.
• To analyze the relationship between AON community structure and key environmental factors.
• To understand the spatial heterogeneity of AON communities within a landscape CW.

Main Methods:

• Analysis of amoA gene transcripts to identify active AON communities.
• Quantitative assessment of AOA, AOB, and CMX amoA transcript abundances.
• Correlation analysis and canonical correspondence analysis (CCA) to link AON communities with environmental parameters.

Main Results:

• Diverse amoA transcript phylotypes of AOA, AOB, and CMX were identified.
• Significant shifts in the abundances of AOA, AOB, and CMX amoA transcripts were observed between inflow and outflow sediments.
• Ammonia and pH were identified as key environmental factors influencing AON community structure.

Conclusions:

• The active AON community in CWs is diverse and exhibits spatial heterogeneity.
• Ammonia and pH significantly shape the community structure of AON groups.
• This study provides a valuable reference for future research on nitrogen removal in wetland systems.