Phosphorus Removal and Storage Polymer Synthesis by Tetrasphaera-Related Bacteria with Different Carbon Sources

Tetrasphaera are polyphosphate-accumulating organisms (PAOs) prevalent in wastewater phosphorus removal systems. However, their metabolic versatility on carbon sources and correlations between carbon and phosphorus metabolism have not been fully elucidated. In this study, we identified a new clade of Tetrasphaera as the dominant PAO in a lab-scale phosphorus removal reactor. Both phosphorus release and uptake by Tetrasphaera-PAOs were more efficient with acetate than with glycerol and glucose. Fermentation of glycerol and glucose provided 4 and 1.7 times more energy than poly-P hydrolysis, and the trade-off between the two processes resulted in poor phosphorus release. Raman-fluorescence in situ hybridization suggested that polyhydroxyalkanoates (PHA) were synthesized from acetate. Glycogen, on the other hand, was the key energy storage compound formed using glycerol and glucose. Aerobic phosphorus uptake with acetate was 4.4 and 1.8 times more efficient than glycerol and glucose due to the additional energy supplied by PHA hydrolysis. The metabolic versatility and fermentation capability of Tetrasphaera-PAOs supported their prevalence in EBPR and underlined their potential metabolic interactions with other populations in the community. This work adds to our understanding of the genetic and metabolic divergence of Tetrasphaera-PAOs, providing useful information for the optimization of wastewater phosphorus removal under varied carbon source conditions.