Exploring the Shift in Structure and Function of Microbial Communities Performing Biological Phosphorus Removal

Area of Science:

• Environmental microbiology
• Wastewater treatment
• Metabolic engineering

Background:

• Enhanced biological phosphorus removal (EBPR) is crucial for wastewater treatment.
• Microbial community structure significantly impacts EBPR efficiency.
• Glycogen accumulating organisms (GAOs) can compete with phosphorus accumulating organisms (PAOs), hindering EBPR.

Purpose of the Study:

• To investigate the impact of a short-term pH shock on EBPR performance and microbial community dynamics.
• To identify the microbial players responsible for EBPR deterioration and recovery.
• To gain insights into the metabolic capabilities of different Accumulibacter clades.

Main Methods:

• Operation of a sequencing batch reactor (SBR) for EBPR.
• Application of a short-term pH shock (7.0 to 6.0).
• 16S rRNA gene pyrosequencing for microbial community analysis.
• Genome binning using a bi-dimensional coverage method.
• Comparative genomic analysis.

Main Results:

• A pH shock caused a complete loss of phosphate-removing capability and a bloom of GAOs (16% of bacteria).
• EBPR performance recovered over time, with a shift in dominant Candidatus Accumulibacter (Accumulibacter) clades from IIC to IIA.
• GAO populations significantly decreased during recovery.
• A complete genome of Accumulibacter Clade IIC was retrieved, showing >90% completeness.

Conclusions:

• pH fluctuations can drastically alter microbial communities and impair EBPR.
• Accumulibacter population dynamics are key to EBPR recovery.
• Comparative genomics revealed distinct nitrogen metabolism and carbon fixation abilities among Accumulibacter clades.
• These findings can inform strategies for selectively enriching specific Accumulibacter populations for improved EBPR.