‘Candidatus Pseudomonas Phosphatis’, a novel Polyphosphate-Accumulating Organism in Full-Scale Enhanced Biological Phosphorus Removal Plants

Project Description

Applied Microautoradiography combined with Fluorescence In Situ Hybridization (MAR-FISH) to investigate key microorganisms involved in biological phosphorus removal in full-scale wastewater treatment plants.
Focused on identifying uncultured Pseudomonas species with potential as polyphosphate-accumulating organisms (PAOs).
Developed and used novel oligonucleotide probes targeting Pseudomonas-related small rod-shaped bacteria in the microbial community.
Aimed to understand the metabolic capabilities and ecological role of these bacteria within the enhanced biological phosphorus removal (EBPR) process.

Identified previously uncultured Pseudomonas-related organisms within the Halomonadaceae family as active phosphate-accumulating bacteria.
These bacteria were not detected by commonly used probes for Gammaproteobacteria (e.g., GAM42a) or even the general EUBmix bacterial probes, indicating a novel group within the community.
Demonstrated ability to uptake orthophosphate (Pi) and short-chain fatty acids such as acetate and propionate, under both anaerobic and aerobic conditions.
Observed polyhydroxyalkanoate (PHA) storage in anaerobic environments, with phosphate uptake and growth only in the presence of oxygen, showing no denitrifying activity.
Quantitative analysis across 23 full-scale EBPR plants revealed that these organisms comprised 3–5% of the bacterial population, often in higher abundance than the well-known ‘Candidatus Accumulibacter PAO’.

Successfully identified and characterized a novel group of Pseudomonas-related PAOs contributing to phosphorus removal in EBPR systems.
Developed specific molecular tools (new oligonucleotide probes) for targeting and tracking these organisms in full-scale treatment systems.
Provided critical evidence of their metabolic potential, supporting their role as key contributors to EBPR performance.
Generated valuable insights to help optimize microbial management strategies in wastewater treatment operations.

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