Combined Deterministic and Stochastic Processes Control Microbial Succession in Replicate Granular Biofilm Reactors

Area of Science:

• Environmental microbiology
• Biofilm engineering
• Wastewater treatment technologies

Background:

• Granular sludge is an effective and space-efficient method for wastewater treatment.
• The ecological dynamics governing microbial community development in granular biofilms are not well understood.
• Reproducibility of granular sludge formation requires further investigation.

Purpose of the Study:

• To investigate microbial community succession during granular biofilm formation.
• To assess the reproducibility of granular sludge development across replicate systems.
• To identify distinct successional phases and their ecological drivers.

Main Methods:

• Utilized three replicate bioreactors for granular biofilm formation.
• Monitored microbial community composition and diversity over time.
• Manipulated settling times to influence granule retention and selection.

Main Results:

• Identified three distinct successional phases in microbial communities.
• Initial phase showed high turnover and decreased alpha-diversity, selecting for aggregate-forming taxa.
• Later phases exhibited increased stochasticity and niche creation, followed by stable communities dominated by abundant taxa, with minor divergence in one reactor.

Conclusions:

• Microbial succession during granular sludge formation follows predictable patterns.
• Replicate bioreactors demonstrate high similarity in community assembly and overall performance.
• Ecological factors like selection and drift influence community structure, but robust performance is maintained.