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Genome-Resolved Metatranscriptomics Provide Insights on Immigration Influence in Structuring Microbial Community
A Y A Mohamed1, Laurence Gill1, Alejandro Monleon1
1Department of Civil, Structural & Environmental Engineering, Trinity College Dublin, The University of Dublin, Dublin D2, Ireland.
Environmental Science & Technology
|March 19, 2025
Summary
Immigration significantly impacts microbial communities in wastewater treatment, with larger granular sludge resisting newcomers better than smaller flocs. Understanding influent bacteria is key to optimizing aerobic granular sludge system design and function.
Area of Science:
- Microbiology
- Environmental Engineering
- Wastewater Treatment
Background:
- Microbial community assembly in wastewater treatment is influenced by immigration and species sorting.
- Bacteria in influent wastewater can significantly affect treatment system functionality.
- Aerobic granular sludge (AGS) systems rely on microbial aggregates for efficient wastewater treatment.
Purpose of the Study:
- To investigate the contribution of immigration to microbial community assembly in different-sized aggregates within an AGS system.
- To understand the activity and role of immigrating microbial populations in AGS functionality.
- To compare the susceptibility of granular and flocculent sludge to immigration effects.
Main Methods:
- Genome-resolved metatranscriptomics was employed to analyze microbial communities.
- Analysis focused on differentiating between immigrating and resident microbial populations.
- Microbial aggregates were categorized by size (granular >0.2 mm, flocculent <0.2 mm).
Main Results:
- Negative-net-growth-rate populations, sustained by immigration, showed significant activity and contributed to AGS functionality.
- Sulfate-reducing bacteria, fermenters, nitrifiers, and glycogen-accumulating organisms (GAOs) in influent were identified as key immigrant sources.
- Granular sludge resisted immigration effects, while flocculent sludge was more susceptible.
- Flocculent sludge harbored active nitrifiers and fermentative polyphosphate-accumulating organisms (PAOs) (Ca. Phosphoribacter), whereas granular sludge enriched for conventional PAOs (Ca. Accumulibacter).
Conclusions:
- Immigration plays a crucial role in microbial community assembly within AGS systems.
- Microbial aggregate size influences resistance to immigration, with larger granules being more robust.
- Influent microbial characterization and aggregate size optimization are vital for designing and operating effective AGS wastewater treatment plants.
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