Bacterial community assembly in activated sludge: mapping beta diversity across environmental variables

Area of Science:

• Environmental Microbiology
• Wastewater Engineering
• Microbial Ecology

Background:

• Activated sludge wastewater treatment plants (AS-WWTPs) host complex microbial communities essential for water purification.
• Understanding the ecological drivers of bacterial community assembly in AS-WWTPs is crucial for optimizing treatment efficiency.

Purpose of the Study:

• To investigate the influence of various ecological variables on the community assembly of heterotrophic bacteria in AS-WWTPs.
• To identify key factors driving microbial community structure and beta diversity in engineered ecosystems.

Main Methods:

• Pyrosequencing of 16S rRNA gene amplicons was used to analyze bacterial communities in 39 samples from eight full-scale and two pilot-scale AS-WWTPs.
• Beta diversity partitioning was employed to assess the impact of ecological variables including influent characteristics, season, process operations, reactor size, chemical stress, interannual variation, and geographical location.

Main Results:

• A core bacterial community of 24 families was identified across multiple AS-WWTPs.
• Influent wastewater characteristics and geographical location were the most significant factors explaining variations in bacterial community composition, accounting for up to 26% of the observed differences.
• Plant-specific families also played a notable role in community structure.

Conclusions:

• Ecological variables, particularly influent wastewater characteristics and geography, are major determinants of bacterial community assembly in AS-WWTPs.
• Partitioning beta diversity is essential for interpreting microbial community variability and identifying drivers in engineered microbial ecosystems.